Most use outrunners. I do, and favor EFlite and AXI models. There are other, cheaper ones, but I have none of them. Lipos and balanced lipos. Lipos should be balanced, that is each cell should have the same voltage. This can be done with the charger itself, I like the FMA Cellpros, or a stand alone balancer like the Astro Blinkie. This is to prevent the cells from having a cell run wild and destroy the pack, usually in a firey manner.
I have read that the Great Planes servos and RX's are made by Futaba and the ones by Hobbico are made by Hitec.
I'm not sure what you mean by using the Lipo pack in a gas engine setup.
Can't help with the B-8 micro servos. I pretty much use only Hitec with some Airtronics.