every time I see an OI it looks better and better,gotta paddle one someday.
: 1. yes, good plan,,don't worry about finishing the gaps untill the hull and deck is together so the exterior seam cloth can be cut for the gaps.

: 2. it's never too late to add more weight. Another layer of 4oz should be plenty unless you happen to be big or HAVE to have 12oz there.

: 3. strength is fine,,you're looking too close

: 4. normal,,and be careful sanding,,it's awfully easy to grind into curved areas when using sufficient grit for large areas, so what is perfectly acceptable "waviness" that is very noticable with all those fill coats can be made more of a problem than necessary with sanding too much EVERYWHERE.

: 5. With 4 fill coats you can start sanding, the weave you are seeing is built up over the glass and in all likelyhood you won't hit the glass, just be careful as you go.

Not having built a strip but done a few s&g you sound like your are doing everything right.