SVE Drifts are good wheels for the money..and no guess work about fitment, since they were designed to go on our cars.
The offset is a bit different on the Boss I believe I have to check into that. I looks like the stick out just a bit more than stock which gives it a more aggressive looking stance.
No, the offset is the same for GT and Boss cars. These wheels are wider, with an decreased offset to push them out further. The stock Brembo and Boss wheels (non-LS) are 19x9 ET42, where these are 19x9.5 ET35 iirc.
Could you run 285/35/19 front and rear without them sticking way out?