i can pick up a 2015 RG special front wheel, tire, rotors with no miles, will it fit on my 2011 SG,they both have ABS, also can i use my fender

 

yes

...next

 

You could, but why would you want to? That low profile tire and wheel may look good, but I'd trade it for a smaller wheel and a tire with a taller sidewall in a heartbeat. That tire can't absorb bumps effectively enough, and now I'm looking at a damaged wheel as a result. Stick with your larger tire...

 

Yes the hub assembly would be the same for both bikes!!

And you will be able to use your stock fender.