If you like the idea of startups, go join one, but don't try to start one first thing out. There are exceptions of course, but in general I think you'll be more successful if you have at least a few years of work experience to learn patterns that work, that don't work etc. Plus unless you have an amazing idea, come from a solid school and/or have connections already getting up and going will be that much harder. If you go work at a startup, gain some experience, contacts etc you'll be more successful when you do your own startup.
2. Take a break. Go travel somewhere and get your mind right. Don't be in such a hurry to jump to the next major thing. You seem fairly young so you do have time.
Consider higher level degrees only if you done one or two.