Hey welcome to the madhouse! Enjoy your new bike
My thoughts on the respray would be don't - you could buy replacement fairings etc. on ebay & a Bagster tank cover. That may not be cheaper, but doing it right & selling your own you could break even
Or, hopefully someone else will tell you about resprays.
Why do you not want aftermarket stuff? some of it looks way better then Suzuki stuff & is far cheaper. Esp belly pan, Poly26 looks way better than Suzuki but OEM seat cowl, yes only £42
2) Yes I do believe Fabbri is the only wind tunnel tested screen.
4) Yes they can, but if you buy a quality one with a lifetime guarantee you'll be fine