toltec

Well, not linked content automatically but if you use a document that includes an embedded document, there is a Replace Document option

So, if you amend and save the original file, click on Replace Document in the document where it is embedded and you can reload the amended file, which has the advantage that it retains the cropping and position you set first time around.
Edit Document converts it into an editable file but is not much use in this case.
Not perfect but if it gets the job done without wasting hours of your time . . . 

Not to mention, (in more or less most requested order)
Crop page
Image tracing
Path offset
Perspective Moulding
On screen Measurement tool
Set ruler origin
And don't even get me started on Affinity Publisher 
Honestly, I don’t know what the dev' team do all day 
 
P.S. Only kidding guys, keep up the good work. 

I said I was designing something for transparent media. It's a piece of clear plastic. So yes, I am designing elements in white, because that's exactly what I want.
If I create a new document, I get a page with white background and no apparent way to change it. That's lame.

Or change to Outline View Mode and click on the outline of the object you want to select.

If you open the Character panel, put the cursor between two characters and you can adjust the kerning.
You can drag on the  V/A bit, hover over the text value and turn the mouse wheel, or type in a value.
 

And again somebody, who declares his actual favourite feature to be a „rudimental“ and „fundamental“ one.
We finally should ask all the forum members, what are their 5 favourite features and urge the Affinity team to put all the results (I think, these are about 15000) „to the top of the list of features in the next (sic!) update“. 

You can just paint on the mask layer. Make sure just the mask layer is selected by clicking on the mask layer thumbnail (see below), choose a Paint Brush and either black paint (to add to the mask and erase the image) or white paint (to remove the mask and reveal the image) and paint on the mask layer. As you do, you can see the effect on the image.
You can also paint in grey for a semi transparent mask.

 
If you  right click on the mask, there are also some Edit options

Edit Mask displays the mask as black and white.
Refine Mask loads in into the Refine Selection panel.
Release Mask just moves it outside the image layer. So it is no longer nested.
P.S. If you are using Affinity Designer, you will need to be in Pixel Persona to paint on it.
 

Not 100% sure what you mean. They are the same layers and the same document.
 
If you hide something in the Photo Persona, it is definitely hidden in the Export Persona and wont output, although you can retrieve it (make it visible) using the buttons on the layer in the Export Persona.
If you hide it in the Export Persona, it is still visible in the Photo Persona, but wont output if "Don't export layers hidden by Export persona" is ticked". Which might lead to a bit of head scratching which is why it is unticked by default, I guess.
Like a lot of options, somebody will find a use for it.

To be perfectly and brutally honest, it wont help, at all 
If it is a multi-page document, you would probably be better of with Microsoft Word using one of their templates. There are thousands of them available for free on the web, many look pretty decent and they are fairly easy to customise,. To achieve the same results in a "blank page" program like Designer is going to take an awful lot of learning and hard work.
Anyway, most designers simply copy something they have seen and "adapt" it for their own needs.
 

I have to select the Artboard Tool to rotate the Artboard which kind of makes sense.
Also if you send the document to be edited in Photo or open it in Photo and there are multiple Artboards it will rotate all Artboards as if it is a single canvas.

Welcome to the Serif Affinity Forums, Nancy.
You’ll get an elliptical selection outline if the ‘Feather’ value is large. Go to the Context toolbar and set it to zero if you want the rectangle to have sharp corners and sharp edges.

I think that rather than use slices, I would create a "cropping" document.
Turn off the visibility of the Island Waterpark logo layer and save the document.
Create a blank Photo document at 1140 wide by 881 (?).
Go File > Place and you can "place" your entire document as an Embedded Document, effectively as a single image. You can move it around and resize it, just like an image until you get the area you want. When you output it File > Export, you wont even need to set anything in the resize boxes.

I can't simulate it exactly but this is about what I would expect. High Quality at 80%. At medium Quality (40%) it was 505kb.

All this takes literally seconds and would pretty much solve all your issues, I hope 
 
Is having a small file size very important ?
This was not good to start with (screengrab) but I compressed it with RIOT and got it down from 642kb to 241kb with little change in quality. It would be much better with a first generation image.


http://luci.criosweb.ro/riot/
 

To be perfectly and brutally honest, it wont help, at all 
If it is a multi-page document, you would probably be better of with Microsoft Word using one of their templates. There are thousands of them available for free on the web, many look pretty decent and they are fairly easy to customise,. To achieve the same results in a "blank page" program like Designer is going to take an awful lot of learning and hard work.
Anyway, most designers simply copy something they have seen and "adapt" it for their own needs.
 

Shouldn't that have been spelled "discovered by Humphrey Davey" ?
Oh never mind  e's dead now anyway.

In english yes, i used the dutch spelling

To be perfectly and brutally honest, it wont help, at all 
If it is a multi-page document, you would probably be better of with Microsoft Word using one of their templates. There are thousands of them available for free on the web, many look pretty decent and they are fairly easy to customise,. To achieve the same results in a "blank page" program like Designer is going to take an awful lot of learning and hard work.
Anyway, most designers simply copy something they have seen and "adapt" it for their own needs.
 

Damn, another one of those "Specsavers" moments.
Or maybe a "Senior" moment, I remember when er, what was it again ?

Aluminium was discoverd by Humphry Davy, first calling it aluminium changed the name later to aluminum. 

But that’s exactly the point! In American English it’s spelled/spelt without a second “i”, and their pronunciation is consistent with that. British English pronunciation is much less consistent with spelling: furzample, “centre” derives from French but we say “-ter” instead of “-tre”. And don’t get me started on English surnames like Cholmondeley and Featherstonehaugh, or Scottish place names like Kirkcudbright and Milngavie....

No, I used Photoshop or Xara studio. I just really like Photo so was very glad when it appeared.
I even have a Linux machine. It stops the door closing 

@toltec it seems for my purposes your modified approach is working best, at least for what I'm trying to achieve while retaining some skin texture. 
It's also likely that to achieve best results, a global solution may not work quite as well as paying attention to specific  zones of the face one at a time. For example, stubble is rarely exactly even, and also the angles of certain portions of the face may present stubble more prominently than in other areas thus requiring more aggressive adjustments.
This has been an interesting practical exercise. Thanks for all the input.

No, I used Photoshop or Xara studio. I just really like Photo so was very glad when it appeared.
I even have a Linux machine. It stops the door closing 

Yes you can - it's called "volumetric forecasting" and there are shed loads of companies who do nothing but forecast  what will happen to a new product.  I'm going to take a wild stab in the dark and suggest that Serif have already done this.

Would love to see a sample image of that. New techniques are always great to learn 

I went for removing much more of the stubble than the tutorial version. If you look, there is also some very ugly, mottled black and white stuff left on the subjects chin.

tutorial version

I cleaned it up more but there was not much more skin detail to work with in the first place. I expect it might be a bit better with a similar amount of stubble left in, or a bit more light reflection. A matter of taste I suppose.
It was a bit hard working on a fairly low resolution web version. Better to work higher and reduce later. I would be interested to try with a better image, if you have one.