>>1994689high spec steel tubing can be 1/4 of a millimeter in the centre of the tubes, but bottom bracket shells are way chunkier, and they're filled with grease. Not really a problem area for rust aside from a siezed bb.
That doesn't look bad. Just surface rust. You can just clean it off with a solvent, wd40, whatever, and something mildly abrasive. I would strip, clean and wax the frame. Maybe spray internally, or just the chainstays. That's usually where bikes rust out as water can pool there. Also chainstay protectors can cause serious rust issues so check that if there is one.
Paint touch ups aren't hard unless you're precious about the look. Pic rel is an example i did. Basically just scrape the rust off, clean, mask, rust converter primer (dries black) and then spray.
Pic of the whole bike? Must be pretty awesome. I have something with similiar tubeset and it's one of my favorite bikes to ride.
