You will get started much quicker if you use the .ma or .mb file and open it in Maya. If you don't have Maya, the .fbx will import into most any 3D software but some minor elements won't carry over. If the rig doesn't function properly when imported as .fbx, it may just need a little extra work on your end to make the proper connections again.
And to answer your second question; yes experiment! It's free so there's nothing to lose :)