Right after I installed it, it came loose in places on it's own. (I used cove adhesive to compensate there.) Yet where the self-stick stuck, it stuck well. I don't think it would tear finished wood in good condition, but it will doubtless peel paper and paint on wallboard in places--especially if it has been there for a while. Even on nicely finished wood or metal it will at least leave a residue. A little lemon or orange oil cleans it up nicely. Just be prepared for some possible patching and smoothing on less sturdy materials like wallboard.
I don't see a reason why not. It works fine in my basement. Depending on the condition of your garage wall, you might want to use cove adhesive though. If it is smooth, you can use the self-stick. If the wall is cement, or a little rough, plan on cove adhesive to fill the gaps and give a long lasting grip.
No, this product is intended for use on drywall.
it has a very light sheen.
Probably. It's a bit flexible, so I wouldn't expect it to crack, but I didn't try that.
I bought this to use on painted wood paneling and it didn't hold. I ended up purchasing an adhesive (I think I got locktight) and applied it using a caulk gun. I think it would probably stick to brick if you used extra adhesive. It might not look the best though.
I doubt it would. It didn't stick on painted concrete block.
Just keep it warm, typically to room temperature, and It will flatten itself out as you work with it.