Graphics question...

Yes to both.

 

Depends on what the next GPU will be.
If it is just a Intel HD 5200 and nothing dedicated the 650M is quite a bit better. 650M is 20-40% faster in games and about equal to somewhat slower in general processing.
If it is replaced by a 750M, it is a mixed bag. The 750M is likely to be somewhat faster but only due to clock speeds. You can expect to be able to over clock and 650M to a performance level that there isn't really a difference to a 750M. 750M is just a 650M with a different turbo mode. It is the same chip.
If they replace it with a 760M which should be a possibility (not the highest one though) there might be quite a bit of additional performance but nothing game changing. It is more potential but it is still the same architecture, same process node, basically similar energy efficiency. A 760M is basically double the 650M in cores but comes with slower clock speeds.

The chances for no cMBP refresh is fairly high. I think well above 50%. I wouldn't rule it out completely though. The chances of an HD 5200 only retina vs. one with a dedicated GPU is 50:50 I think. A 760M would still be a lot faster than a HD 5200 especially in games. If they go for a 750M, they might as well just get rid of the dGPU altogether IMO.
Even a 760M will only be about 35-40% faster than a 650M@900Mhz.