1. the balancer makes all cells in the pack the same voltage 2.well my guess is that it will be close, your nimh will hold more mah, but also at the expense of being a lot heavier, so considering the weight savings, you should get more flight time out of the lipo. 3.the more the volts, the more the power, so more power with the nimh. 4.my guess is that you should get the 3cell lipo, not the 2 cell, it sounds like that is closer to the voltage that you want to run, if you go with the 3 cell lipo then its a whole diff story, you will then BY FAR have more power than your nimh and more capacity as well, of course i dont know what the rest of your setup is. if your long range plans include brushless then 3 cell lipo is most likely what you will want. 5.you will be able to charge it at 1 amp max, im not sure off the top of my head what amount of time that eqates to, but just guessing.... maybe an hour or so.

if you give details of what motor and speed control you have, we can answer more specific.