When will too much +/- offset create problems?
 

I'm not talking about hellaflush or anything. I'm more concerned about the negative effects such as bearing failure and other potential downsides. I've heard Subarus don't handle low offset wheels that great (Not sure if it's true).

Is there a way to prevent damages other then close to stock wheels? I'm mostly looking at 17x8 with around 35 to 45 offset wheels.

In doing the same research, your proposed setup would work with 35 offset. For close to stock handling 45 is probably more appropriate.

Search scrub radius and it explains what happens with extreme offsets. In theory, extreme offsets will hurt handling and more stress on hub bearings and suspension.