You can convert nitros to electric, but you're better off buying purpose built electric airframes. The nitro airframes are more rugged (and thus heavier) than they need to be for electric.

If you're just getting started in electrics, I'd suggest getting a foam park flyer of some sort. The smaller park flyers are cheaper to equip, and foam airframes are super easy to repair. If you have some 3S 2200mAh packs, then the park flyer sized planes would be perfect.

To fly larger planes with those packs, you'll have to double them up in series or parallel, since the larger planes require more power.