1. Yes
2. Yes, depending on the charger you use. You
cannot with the cellpro that eveyone recommends.
3. Yes, the DA ignition can handle the full charge voltage of an A123 pack. The only way to charge the pack externally would be to build your own pack with a seperate charge lead. But remember, both the Power expander and the ignition cutoff will continue to draw a small current, even when off, and it is highly recommended that you disconnect them after each day of flying or you can run the batteries dead.
4. I have a thunder power 1010C with the version 2.3 firmware upgrade, making it A123 capable, and I can balance charge or just plain charge with it - this is not an option with the cellpro - you must always balance charge.
I also bought some cheap chargers here
http://www.batteryspace.com/index.as...OD&ProdID=3286, which will charge at 1 amp until fully charged and then shutoff. They aren't fast, but they are cheap and easy.