Holes in all the ribs isnt going to make any appreciable difference in strength or weight either.Most of the strength in the wing is dependent on the design and constuction of the spars.Make sure the holes are big enough to easily fish the servo lines through.I stack my rib blanks about 10 at a time and use a hole saw in a drill press for this job. Installing rolled tubes of newspaper works well,but make sure you install these before you join the wing panels,and put on the wing tips.The biggest weight savings (insert BIG IMO !),is using plastic iron on covering, particularly for the wings,(I prefer Ultracoat),being careful about how much epoxy glue you use,and watch the paint build up if you go this route on the fuse.
I would not worry too much about toe-in at this point.More important is no toe-out, and the placement of the gear in relation to the CG.Using an easy thumb on the throttle,and learning to use rudder during and after the takeoff is a must.However,the design is not in the least squirrly regarding ground handling,and tail high takeoffs are easy and pretty.I think your first takeoff,and full stall landing will make you an Ace fan for life!
Im not sure what you mean by balsa ply,but make your firewall out of the 5 or even 7 ply wood sold by your LHS,or places like Balsa USA.
Feel free to keep the questions coming,but lets do it in this forum,not E-mail.Im sure there will be other opinions on some of these subjects,and that is all to the good.