Re: the fuselage--you're right: the front, from #2 forward, is a completely separate structure that the front of the wing is built around: MM beams have 1/16" ply floor full width, full length--that's what that crazy crosswise grain on top view is trying to show--and looks like it extends out into those wedges labelled "Plywood carry-thru", all one piece. Then the engine cowl is most of the top back to #2, with some small side pieces, shaped as your sketch except ending at the bottom of the MM beams (1/8" thick? top view), the 1/2" solid block being the bottom, back to #2 also. Then the rear part of fuselage, from #2 back, would have a cutout for the wing and slip on from the back. All the more reason to eliminate some of the formers/braces back there; that whole structure is really irrelevant; doesn't hold anything but itself--the plane would fly without it! Sure makes that front end beefy. I still think some strategically-placed holes would be in order.
On the gear, how would that compare weight-wise to the 1/16" wire shown? That #2 former could maybe become balsa without the gear anchored to it, that would help the weight loss too; but speaking of that, how would you anchor your alternative? If moved a little forward, the ply. plate could be recessed flush into that solid balsa block, perhaps. Would be nice to anchor it directly to the MM beams but that would leave quite a gap underneath.
I agree, too, the holddown screw location for the cowl is not good. Seems like moving it to the back and using alignment pins at the front might leave the front a little unstable up-and-down-wise. Why couldn't a block be put in behind the engine, just in front of the step-down of the sides, to hold a blind nut for the holddown screw there? The pins, I think, either front or back, would still be needed.
I'm still having trouble reconciling the various wing spars with the notches shown in the rib patterns. Help me out there, would you?
--Ray