Hi,
If there is enough time between rounds you can get away with one lipo battery. They are not like the old cells, they can be re-charged multiple times a day. (Two will make it easier / less of a rush to get things charged up.)
Charger lots of options. If you are starting off, one that works on 12v and mains (built-in) is ideal.
Something like this for a charger is a good option:
http://www.cmldistribution.co.uk/cml...tId=0000006811
Lipo it would depend on where you are going to be racing, if you need to be using a battery that is on the BRCA battery list.
Don't forget a lipo bag for charging.
MiCk B. :-)