The 8.5"s will fit in the front no problem. I run 8"s in the front on my E36. How offset works is where the hub is in relation to the wheel. I believe in you case the best option for you is to go and measure how much room you have between the feder and the wheel, and how much room you have between the wheel and the strut. The total size with tire width will tell you how wide you can run with no fender rolling. If you want to run 9.5"s and it does t have the room find a set with the hub set back into the rim more. That way the majority of the rim will stick out and clear the strut.
Here is a tire rack article on wheel offsets:
And here is a wheel offset calculator that might be able to help:
I should mention my 18"s have a -40 mm offset. Other options include running wheel spacers to flare the wheels out more. Might be a better option as they arent too expensive.