I've got some newb lipo Q's for you guys

[Sammus]

1) depends what the other ratings on the pack are and what other gear your running, (particularly what truck :P)

2) you would buy something like a 2s and a 3s, put one on each side of the truck and run them in series

3) I guess that depends what ESC your running.

3) Not 100% on this one, the mah is just a measure of how much charge is in the pack. Since lipo's are capable of delivering much higher current that nimh packs, what theory i know and understand tells me it would be less runtime or the same at best. For example if the nimh packs are the limiting factor of your setup now, then the lipo packs will deliver the extra current where the nimh packs cant so will probably be depleted quicker.