Thanks for all responses guys! Much appreciated!

Mock-up build #1 fitting the neck

Straight out of the box, the neck just fitted (not) in the pocket: fraction too wide and can't get it all the way in:
wood at the lower corner pocket seriously stretched after some force. Also the the corner radius of the neck and pocket don't match.

Click image for larger version. 

Name:	2016-07-22 19.41.10.jpg 
Views:	320 
Size:	336.9 KB 
ID:	12748Click image for larger version. 

Name:	2016-07-22 20.23.23.jpg 
Views:	326 
Size:	345.1 KB 
ID:	12749

As this body has no holes for the bridge yet (I checked the 4 point neck alignment tutorial), I decided to sand down the neck at the lower end a little for a comfortable fit and aligned along the long pocket edge. Tried to get is as far in as possible, now at a gap of ~0.5mm.
Click image for larger version. 

Name:	2016-07-23 22.15.20.jpg 
Views:	340 
Size:	445.0 KB 
ID:	12750Click image for larger version. 

Name:	2016-07-23 22.15.41.jpg 
Views:	349 
Size:	307.0 KB 
ID:	12751
Should I continue to get a 100% fit or is a little gap at neck edge OK tonewise? I mean, 90%+ of the contact area is at the bottom anyway and I don't want to risk sanding it too much making it loose...

For alignment, I measured the body width at the widest part, put a little pencil marker half way. A thin wire in the dead center of the neck across all dots nicely lines up with the mark with the neck fully in and pushed towards the long/top side of the pocket. So, time to start drilling the holes in the neck and use this midpoint as the center for the bridge and pickups.
Click image for larger version. 

Name:	2016-07-23 22.13.47.jpg 
Views:	333 
Size:	352.4 KB 
ID:	12752
For the neck plate, in the instruction video the black rubber thing is used as well. I would put the metal plate directly on the wood like for real Fenders. Any thoughts on this?