1. If the charger has balancing plug, then it will work.

2. Charging at 3 amp would take a little over 1 hour. Charging at 4 amp should take about 1 hour.(some one correct me if wrong, but i think it should be correct)

3. Get a charger/balancer combo would be good enough. Also with Li-po,make sure your car can handle the extra if you go with brushless. I have a charger I bought from ebay from Hong Kong, it can charge Ni-mh, nicad and lipo and balancing too. Great for $60.. All my frds have been using it for over a year without any problem.