These are G-instances and graphics is one of the primary use cases for this instance (and for the previous G2 instance). The M60 is the top part with GRID support built in. A GRID license that allows you to use the GRID driver is part of the offering.
Disclosure: I own HPC for AWS (among other things) and used to own instances
Not really. Typically there were reasons you would stick with older generations, such as M60s having very poor fp64 performance. If you want fp32, it gives a bump over the K80s currently in there. However, the P100 would have been the most logical path since it doesn't cripple fp16/32/64.