Hi Ken-
I went the standard wings and QB fuse route. Best route is really up to you. Wing is relatively straight forward with fairly redundant tasks. I went this route only because after building the tail section, I felt more comfortable building the std wings since the process is essentially the same as tail, just larger scale. Some chose QB wings to avoid building the tanks and dealing with pro-seal. Fuse is a little more complex, but with pre-punched kits now, should be straight forward. The QB fuse still has plenty of work to complete. Comes down to what you want and possibly how good of a deal you get on the QB wings. Get a set of RV8 build videos to get the big picture. I'd suggest you bring someone that has built an RV with you to inspect the quality of work done so far. Could be some hidden items requiring rework.
Call Vans to get the the full inventory list.
Center section depends on the vintage, I don't know the cut off but at some point they no longer match drill center section to wing creating a unique set. Newer kits have wing and center section drilled with CNC and do not need to be a match set. You will need the kit serial number and call Vans to verify what you have and how to proceed.
The std wing kit box is longer because they come with the fuselage longerons to save shipping on fuse kit. The std wing kit is already long and incremental length for longerons makes more sense to ship with wing kit.
Best advice is to call Vans and they can answer all your questions. Won't be a problem.