Yes, Vector Flight is good enough to throw some scrap covering in the box, in case you ever need any. Don't worry about the epoxy on the wing joint. It's just important that you got the two pieces joined on a flat surface, and as long as the two are tight together, you'll have no problems. A little epoxy goes a long way.
As for the battery packs, if you have enough open sockets on your receiver, you can plug in a second battery pack, and/or switch assembly into any open socket. That way you'll have two battery systems. If one switch or pack goes bad, the other will still be working, and with both turned on, you'll also have double the mah. 2 600mah = 1200 mah. However, I believe you'll have to charge them, one pack at a time.