Royal with Cheese
1. The wheels should work, people use 15x8 +0 all the time, sits flush, so yours would be sunk .5" in from that.
2. Your choice of springs will not affect wheel offset.
3. a 205 is, IMO, a bad choice. I have 15x7 with a 195 and the sidewalls are about 90 degrees. I'd want to run my 195s on a 8 inch wheel for a little more stretch, 205s would make the steering feel numb.
4. I like your avatar!
Can you fit 185 on a 15x7 as well ? With a 50 or a 45 sidewall ?