Can i double max current drawn, putting batteries in parallel?
Yes, this can and is commonly done in the RC modelling crowd with lithium polymer batteries. Just make sure that both batteries are at the same state of charge (voltage within 50mV) before hooking them up, or you might damage the less charged one by charging it out of spec.
You can even use batteries of different capacities in parallel (but never in series!) as long as they have the same cell count and battery chemistry.

It is also possible to charge multiple batteries in parallel. Again, make sure that the batteries are not too mismatched in voltage before connecting, and make sure that you connect the balance plugs in parallel when balancing (which you should do on every charge).  

Your maximum current estimate is correct, but keep in mind that cheap LiPos often overstate the maximum discharge rate somewhat.