I don't know how with only 3000 miles on it it needed so much fixing but the engine is fine and I just sealed the tank as it was showing rust inside from ethanol fuel
Get used to it. Mine could be the twin of yours, except that it had only about 1700 miles on it when I got it about 18 months ago. I get about 250 miles to the repair job. I also got a "great deal" and wondered why the mileage was so low. I think I knew in the back of my mind, but the bike fascinated me. Still does (but not nearly as much...) Right now it has been sitting idle for the last 5 months while I try to replace the wiring harness, which was a total piece of junk. Apparently, no two wiring harnesses are ever made exactly the same, and the wiring parts all cost "Drug Money" and are the most favored victims of the so-called supply chain problem. For example, my bike does not have the connector to which you refer. The harness I am doing battle with now is supposed to be OEM design and manufacture for make, year, and model. HA! The wires that all go into the headlamp plug on my original harness are all dangling unattached in the new one, and several of the connectors do not match-up correctly. I think RE takes Indian schizophrenics and puts them in their electrical departments.
Your fuel tank had rust in it because that is the way it most likely left the factory. Mine was rusted too.
Up next, or at least soon:
*Brake calipers rebuild
*Sprag clutch replacement
*Multiple, sundry, and never-ending oil leaks
*Multiple, sundry, and never-ending electrical problems.
*Etc., etc., etc.,
The more I write this, the less fascinated I become with my RE. Thankfully, I have 3 other bikes that require only routine maintenance and can actually be ridden!