Everything should not need support. The fact that most everything needs support is a symptom of how crazy the software industry is.
Yeah, and the way that's done is by refactoring things, removing buggy/deprecated things, and not adding any more new features/requirements... So, pick your poison, I guess? I'd love to go move on to the next job as much as the next person, but somebody still has to be paid to do those things. I don't see what the significant difference is there with free-with-paid-support, if you pay for it up front you're still paying the same cost.
Yes you can. You can spend some time to stabilize, and then add new features on top, then stabilize again if needed.
The distinction is cruicial.