Hi,
One of my main reasons for purchasing AD was for the creation of Android launcher icons and Play Store graphics etc. so hopefully I'll be able to shed some light. There might be better ways but this works for me...
I've set up an AD 'template' with three Artboards:
A large 'scratch' artboard at no particular size for testing ideas etc.
A 1024x500 artboard for the Play Store Feature Graphic
A 864x864 artboard (as recommended by Google here) for the 512x512 High-res Icon and the launcher icons
I've set up the export persona with a slice for the 1024x500 artboard and another slice for the launcher icons etc. Within the launcher slice I've set up a number of export sizes corresponding to each of the various icon sizes required for ldpi, mdpi etc. and for the 512x512 hi-res play store graphic, each at the correct dpi and size. Each of the output files are also set to automatically go into the correct folders (mipmap-mdpi etc.). For each of the launcher icons I've set both the width and the height for the output file. You can set these by either picking from a drop-down or by entering the size manually. For instance; for the mdpi I've entered '48w, 48h' and in the export settings fly-out I've set 160DPI as well as the folder it needs to go into.
I hope that makes sense! I've included some screenshots to make it a bit clearer.