As Juanlu001 said, there is really no such thing as too many questions, as long as they are good questions.
However, as you probably know, on Stack Exchange we expect people to do some research before asking a question. Research usually entails searching Google (and/or Bing, Yahoo, etc.), reading documentation, checking mailing list archives, searching SciComp.SE and Stack Overflow for relevant questions that have already been asked, and even tinkering around with code a bit. The point is that asking a good question for an SE site takes some preparation, and you can't ask all that many questions if you're really putting in the effort to research each one.
On the main trilogy sites (Stack Overflow, Server Fault, Super User, and Meta Stack Overflow), users are limited to 6 questions per day. That limit doesn't apply to this site, so there's nothing stopping you from posting 10 or 15 questions in a day. But if you reach that point, it does make people start to wonder whether you're really doing your prior research, and more importantly, it should make you wonder whether you're really doing your prior research (or whether you have no life and are spending all your time on Stack Exchange :-P).
The other thing to keep an eye on is what kind of a response your questions are getting. There is a quality filter which prevents users who ask many bad questions (as indicated by downvotes and deletions) from posting further questions until they improve the quality of their contributions. Your question quality is high enough that you're in no danger of tripping this filter (unless you've asked a ton of deleted questions that I'm not seeing), so don't worry about being banned, but do keep the spirit of the filter in mind, which is that if your contributions are not being well received by the community, you should take a step back and think about how to improve them.
But essentially, the main point is that as long as (1) you are putting the work in to make your questions good, and (2) the community agrees that they are good questions, the more the better!
P.S. Another thing I meant to mention but forgot to write at first: making this site a useful resource requires good questions, just as much as it requires good answers. So as long as your questions are good, you are contributing to improving the site, and you shouldn't feel like a leech for doing so.