Hmm didn't think about that, the plug probably does not come on the charger it comes w/ deans, so you will likely have to either

A) get two male deans plugs and change over the truck to deans. And instead of getting the battery w/ traxxas get the one w/ deans instead (rcplanet has them too).

B) get one male traxxas plug and one female deans plug (or I guess you could just snip off the deans and solder the traxxas plug on to the charger) and make an adapter for the charger. I think they sell deans to traxxas adapters somewhere too.

Pair of plugs are <$5 didn't factor that in.

As for a lipo bag that's up to you, you don't NEED one, but its not a bad idea. The hard cased lipos that are ROAR ok'ed (Team Orion batteries are) require that if they "explode" from being overcharged or whatnot they only vent smoke, no flame can be visible in order to pass... With that said I wouldn't charge them on the carpet of your living room floor while you go shopping, but personally I wouldn't have any problems doing it on a solid table under supervision.