1. The owner's manual recommends that the GTS receive premium (89 octane) fuel. I believe it's because of the 2ZZ engines higher commpression that it requires this. I don't think it would destroy your car if you didn't use it but that was "one" of the reasons I ended up getting a GT...fuel isn't getting any cheaper these days.
2. How bad is the dent? Look on eBay and see if you can't find someone who is just selling their intake pipe. Most I think are made out of aluminum so if you took it to an auto repair shop they might be able to get the dent out
3. I have the TRD front and in a year and a half I think I have 2 pin sized chips in my paint
Consider having the paint touched up and getting a 3M clear plastic protection put on there. It's the same thing they put on the front part of your hood at the dealership. Your local dealership could put that on for you but it isn't cheap. The front six inches of my hood cost almost $300