Welcome!
#1: Wash with a strong but clean detergent like Dawn, and wax with a good cleaner wax to seal your finish and keep it looking good. You can always repaint down the road if needed. ( See Alan/ExtremeLX for your repainting needs
).
#2: Personally, I like the factory spoiler, and I wish my SVT had one, but it's all owner preference. If you DO decide to remove it, please, please, please, don't get a huge wing. :rolleyes:
#3: WTF?!? Sold you a car w/no speakers?? yesh? Chances are, the previous own had a system put in, and didn't wanna sell it. So, he dropped what factory stuff he had in and sold as is. Check the usual sites ( crutchfield.com, sounddomain.com, etc ) for some way better-than-factory items.
#4: Wanting to do this myself, but have yet to see a replacement I like. Search in the Aesthetic forum for some pics and ideas.
#5: The SVT Duratech lives and breathes for 92/93 octane. I have yet to use anything BUT Chevron premium or Amaco Ultamite in my tank. The high(er) compression engine benefits from 92 octane. So, spend the extra $.12/gal for the good stuff and you'll have a happy longer lasting engine...er...yeah..
#6: Most SVT owners ( from what I've read ) use Mobil 1 full synthetic; I am one of those. Market research seems to point to Mobil 1's full syn as one of the best. Others have their own preference, so it really comes down to what you think. Full syn oils GENERALLY don't last as long as regular, so be prepared to change it AT or about 2.5k - 3k miles.
#7: I'm of the opinion that if you're good with a wrench, do your own maintenance, and go to Ford at critical maintenance times (60k miles, 80k miles, etc ) for a complete checkup.
Hope that answers your questions, or at least points you in the right direction to find your own answers....Again, by no means am I an authority; do your own research. Enjoy!