RE: Battery Packs
Don't bother with those batteries. They're no good for the high current demands of electric flight. I say this not because I know the cells themselves, but because I know what's typically found on Ebay. Getting good cells for R/C electric flight off Ebay is a crapshoot, and the odds are nowhere near being in your favor. Most vendors on Ebay sell the cheapest crap cells they can find.
Unless they specify a brand name, like Sanyo, KAN, HECell, or GP, it's a pretty safe bet they're not going to perform. You know what they say about something sounding too good to be true, right?