1. I have extended warranty but I do plan on doing mods. I just can't do anything too crazy. Depends on your dealer if they are anal or not. I mean you can probably get away with an exhaust and cool-air intake, but any Tubros or something along those lines that drastically change car performance will be used against you in what the warranty covers. If you buy the Warranty later, depending on the dealer, it's going to cost alot more cause your car is considered "Used." They offered me $1,800.00 which was the cost of the Warranty and I said no at first, then right before the deal was done, they lowered my APR to %1.89(from %2.44) and offered the Warranty to me for $1,600.00 and I took it cause fuck interest.
2. Opticoat really depends on the amount of $$$$'s in your pocket.
3. Tinting wouldn't be a problem unless your %shade is too dark and your get tickets. Idk what the limit is where you are.
4. If you don't want to scrape the bottom of your bumper, get a front lip, something cheap and easy to replace just in case(DIY Idea). Tires are important. Beat Sonic SharkFin cause that antenna though, unless you want the Perrin shorty antenna but it just looks like a CHODE.
5. Before buying just think about all the things you want to do to the car and write them down. Those things might change for you after driving the stock car for awhile but this will easily determine if you want the Warranty or not.
Welcome to the forum and Good Luck on your purchase.
PS: POST PICTURES!