Question 3 is the only one I am qualified to answer. The relevant question here is this: do you already have the skills that graduate schools assume you will have when entering? If not, you’ll need to start over as an undergraduate. If so, then go to graduate school. The people I know who did computer science did not actually need graduate school to get jobs, though the market has changed. If you don’t feel like you are qualified to get a tech job now, I think it is highly likely that you will need to start over.