Hey Sunair,
First off, Welcome to the forum!
1. It's your call, but while the Power pack costs a bit more, everything matches. If you're building from plans, sizing your own kit will be cheaper, but if you're buying a SBK, might as well use the shipping to your advantage.
As far as alternatives . . .
For a tractor build with pod, the CF2822, 8x4.5 prop and 18A to 20A ESC from the B pack aren't a bad combo. More slow than "moderate speed", but comfortably flyable. Be advised, if you buy somewhere else, that motor typically does not come with a prop adaptor or bullets.
For pusher, I've liked the oomph I got from the
Turnigy D2826-6 (2200kv), matched with a 5x5 prop (pick reversed or pusher, if you can find it, but not critical) and a 35A to 40A ESC.
In either case, cheap 9 gram servos like the HXT 900's are up to the task.
2. (see 1)
3. If building from plans, Build and join the wings, but before you put on the winglets, strip off all the foam and cover with packing tape. saves a LOT of weight, moves the natural CG forward (easier to balance) and the packing tape is more waterproof and durable than the paper it replaced. For the balance shift alone, you might consider doing this with the waterproof foam in the SBK.
Take GREAT CARE in the dry-folding and gluing up the wing-halves, particularly in the second wing half. It's VERY easy to fold up the two halves differently (thick or thin). It won't fly much different thick or thin, but if they don't match it will be hard to join the wing halves and won't fly happy.
Otherwise, get the balance right and she's a fun wing. I've built several and been pleased with them all. Good luck and post a few pics once you've got her built and flying
