1) Can a game of commercial quality be made in a swing frame set to full screen?
2) How many months learning will it take to get a basic grasp on animation? Assume I'm pretty much starting at 0.
3) Are there any different technologies (i.e. game engines) I could move to that would greatly simplify animation?
4) Would teaming up with another enthusiast who has a grasp on graphics be a good idea? What are the downsides?
5) Should I backtrack and work through some tutorials on making simpler games, and then return to my main project?
1) I believe, yes. I never sold something though, and I'm happy enough if I get a few people to actually look at my projects. But still, I don't see a technical restriction in the Swing toolkit that would prevent you from making a professionally looking game; it might just be a question of effort.
2) It depends. A lot. If you have a natural talent on understanding how things move, and some talent in painting, you surely can learn it in a few weeks. Otherwise I'd recommend a few months of practising, of course you'll need books or tutorials which teach you the basics of anatomy and kinetics.
3) I have no idea. Either I use 3D tools to render my animations, or pixel them frame by frame. Neither approach is very quick.
4) Yes for sure. Downside? You'll need to communicate, find agreements, and have discussions. It's slower than doing everything yourself, but will result in better quality. A 2 person team has little communication overhead, but it already exists.
5) Hard to tell. To make a game you need:
a) Game design skills (how to make it interesting/fun?)
b) Coding skills (actually bring it alive)
c) Graphics skills (make it look good)
d) Sound/music skills (set mood and atmosphere, give feedback to the player)
e) Storytelling skills (keep the player interested)
... at least. If you lack some of them you can still make games, but it will be more difficult and most liklely players will feel that something is lacking.