[Add word kerning / spacing between words in Publisher]

As far as my typographic understanding goes, kerning is the individual spacing between glyph pairs and tracking is the general spacing between letters of a word. I really only want to adjust the spacing between words. Of course, if you really want to, you can go into each space between words and adjust their width - but this is not a really good way of doing it.
InDesign has a separate feature for this kind of fine-grained adjustment.

[Add word kerning / spacing between words in Publisher]

Currently it is not possible to adjust the word kerning on a line per line basis. It is only possible to apply it on a whole paragraph by selecting a justified text block and adjusting the settings in the paragraph section of the style panel. This task is common in editorial design work, when you want fine control on a text block.
InDesign supports this kind of control.

Keep up the good work!

[Running Headers adds a special character]

I just fixed it (see solution below) – so maybe this is interesting to some. Since I don't know if this is an actual bug or a feature™, I post it anyway.

I really appreciate the new feature running headers field. Unfortunately, I'm getting a bit confused here. In my scenario, I have a chapter number and a chapter title and want to present it on every page. The format I have in the text block on the master page is the following: <Running Header>—<Running Header> but for some reason, I have a line break after the first one which should resemble the chapter number. 
I inspected the characters and found that a invisible character is added after the chapter number.

<0x00> // which resembles a null symbol according to unicode

I also inspected the source field but found no special character after the chapters number.

––––

Solution, kind of.
In my scenario I created the chapter numbers style as a character style instead of creating a paragraph style like I did for the title.
Easy fix was to just use a paragraph style for the chapter number too.