For your company to sponsor you for an H1 visa, it needs to be able to show that it has considerable financial resources (either revenue, or investors). So if in a year from you have a LOI from an investor or revenue, you can show that to the INS for credibility.
As far as the incorporation goes, I think initially its best to have it as a partnership LLC, since it is pretty flexible and gives you enough wriggle room since LLC's are often open-ended and can be structured in a variety of different ways. Once you go big, have your H1B you can think of shifting towards another incorporation model, as most investors would want you to anyways.
IF you have not graduated, then best advice: take a min number of credits while in school and work on the startup till you get decent sized enough that you can attract funding or have enough revenue to get an H1B or an E2 investor visa.
Hope that helps. I know how hard these immigration issues are to wrap ones head around, so let me know if you have any more questions. I have been through it.
There is also a great blog post written by one of the principals at K9 ventures. I suggest reading all of his stuff on visa issues as well: http://bit.ly/nTsGTy (its a text only version since actual page is not loading)