As someone who is getting their MBA online (October 31st baby!!!) I say go for it. You learn so many things that you can carry over into a new position its not even funny. Make sure that the school is reputable though, try and find one that is a top-tier (top 25 or 50 in the nation) business school, whose MBA program is also highly ranked. There is no correlation between MBA program and B-School Rankings. The program I originally started out in was a High Technology MBA, ranked in the top 5 High-Tech MBA degrees in the nation, where as the Graduate Business school for Northeastern was in the top 25 in the country. (this factors in quality of ALL graduate business school programs)
Some of the skills you learn are that you can talk about how not only did you learn all this stuff about business, but you learned more about time management skills, seeing projects through from start to finish, managing cross functional teams, how to produce financials, a better understanding of accounting (you learn business speak too!) etc. . . anyone who looks at a degree from an online school and dismisses it is a fool in my book. My Northeastern MBA that I received online (hopefully :) ) means that I am a proven self starter, and my little piece of paper is just as good as someone who spent 3 years on a campus. In fact I would venture to say that my degree is more impressive because I learned the information on my own through various sources, did it in 2/3s the amount of time that most people will take, and managed to pass by impressing professors (who also teach on campus) with my knowledge, while maintaining above the minimum GPA required to graduate. In my case I think the minimum to graduate is a "B".
As for VC's . . . you will have a better chance of getting through the door with them. They will realize that not only are you passionate about your cause, but you are educated, and they know that you will be more willing to work with them, as they will usually require a significant position of ownership. Additionally, it will be easier for them because you will understand WACC, balance sheets, and your financial projections will be much more believable.
As for 3 . . . that is a choice you will have to make. If you can do school AND start your product, it will be better for you when you go to the VC's.
Again, make sure the degree program is nationally accredited, and the degree comes from a reputable school. At the end of the day, no-one needs to know that you took the courses on-line. (In fact a lot of B-schools make you take some of the more basic courses online anyway)