A 1050 mah battery will only take 2 hours to charge at a .5A charge rate, not a few hours. For that battery 1C would be slightly over 1A and will charge it in 1 hour, instead of 2. And that's assuming the battery is at it's cut-off voltage. If it has some charge left those times could be much shorter. As for the voltage, if that's what you're asking about, 7.75 volts for a fully charged 2S battery is just fine. The rated voltage is a nominal voltage, not a fully charged number. But what you really need to watch is the balance between the two cells. Use a volt meter and check the voltage on each cell. They should be identical - or very close to it. If you get a ballancer then that won't be an issue either.
And, yes, the reciever and servos will work fine on 5.1 volts, but will be faster/stronger if you can upgrade it to 6v.