Aristotle's Nicomachean Ethics: The Intellectual Virtues 

Well--Just because I can "list moral virtues all day" doesn't mean that EVERYTHING is a virtue! There are certainly still things that aren't virtues. And indeed, there are activities that Aristotle says CANNOT be done virtuously--things which, by their very names, indicate that they are bad and cannot be done "in the right way, at the right time," etc. (He gives the examples of murder, theft, and adultery.) But all of this can be true even if we could (as I suggested, somewhat sweepingly) "list moral virtues all day." My point, however, is that there are a great many "good habits" we could list; that it is certainly not confined to just the fifteen or so that Aristotle specifically mentions in NE, or the seven "heavenly" ones a lot of us grew up hearing about, etc.

A good question! But you might mean a couple of different things by it. By "think too much," you might mean continuing to deliberate when it's time for action--in which case, it's not exactly a problem of "thinking too much" as it is "not acting in time." But "thinking too much" might also mean "too contemplative." And here, I think that Aristotle would say "no": Higher contemplation is our highest calling as humans, and the more we can (get to) do it, the better.