3 Battery Questions

Hello everybody..

I have the sabre r/c helicopter and I would like to look into batteries that will give me a longer flight time. I have now a NiMH 650mah at 8.4v.. I have seen these lipoly, but they are usually rated at a 11v and 7.2v. I have heard the 11v lipoly might burnout my motors (I do have a heat sink on my tail motor). Would the 7.2v be enough power for my helicoptor that I am using with the 8.4v NiMH?
--------------------------------------------------------------------------
Also I was looking at my 7cell NiMH 650 mah 8.2 volts battery and I noticed they were all AAA(triple A's). I looked at my AAA (triple A's) Energizer NiMH rechargeable batteries and noticed they were 1.2v at 850mAh. So my question is if i run 7 of these AAA's together would it not give me a battery that would be 8.4v and 5950mAh. Is that dangerous? Do people make there own batteries?
--------------------------------------------------------------------------
And lastly where is a good site that has a good selection of rc heli batteries. (lipoly as well)??????

Thanks for any help