RE: Two Q's (extremely frustrated with batteries)
Check your locale for hobby shops, most shops should have them. Hobby Town USA for sure carries Thunder Power, as it's listed on their website.
[link=http://hobbytownusa.com/StoreLocator/]Hobby Town store locator[/link]
Check out the above link to find a Hobby Town in your area.
I don't know what kind of charger your heli came with. If it has a connector with more than 2 terminals, it's probably a cell balancer/charger and *may* be good to use. Does it have a screen that displays voltage and charge rate for each cell?