Welcome Lewis.
1. Yes. See comment at 2 below
2. Lot's of venues are more comfortable with covers. I think most of them will accept original material if it is "woven" into a set that is familiar to the punters and it is complimentary to your cover material. I'll always remember the gig at a working men's club in Dublin in the mid eighties where the landlord shot over and cut the power off before we were even eight bars into the first of our set of Joy Division and Cure derivatives. Our drummer's dad had got us the gig at his club. Michael returned the favour by thanking the Killester Working Men's Association for being "such bar stewards" at the top of his voice. He chose to do this before we'd taken down our gear so there was a thick oppressive atmosphere for a while before we got out of the place altogether. Fun times.
3. Take a look at the Basschat Build Diaries for inspiration. Even if you don't want to do the work yourself, you will surely be able to refine your ideas for a custom build or a modification by looking at what others have done before.
@Andyjr1515 applied his decal to our Jag bass that he'd modified. It was self adhesive and it got four light wipes of Osmo oil (as I recall). Perhaps he'd be able to save you the extra step of nitro coating with some advice?
My only bit of geekery is that I like large speakers.
After a period of ownership of a weedy little 12W Marshall practice amp I got a Laney combo with a twelve inch cone. Then I got the Ashdown with a fifteen. I then bought a Trace Elliot extension cab with an eighteen inch driver.
If I ever gigged I'd have to get some lightweight gear.
"tank fly boss walk jam nitty gritty you're listening to the boy from the big bad city, this is jam hot, this is jam hot"
Dub Be Good to Me, Beats International.