You've touched upon a large and complicated subject but here are couple things to get you started.
First off, you need to be very clear in your own mind about your venture vs. your consulting work.
Consulting is simple. There are three main reasons to form an LLC as a consultant: you can isolate yourself from liability; you can snag more work as some companies prefer to work corp-to-corp rather than with individuals; and finally, you can utilize various legal mechanisms (such as managing vs. passive partners for example) to minimize your tax liability.
It sounds like none of the above applies to you very much. It's too much hassle to sue someone in a foreign country, companies prefer corp-to-corp for reasons largely irrelevant to outsourced consultants (who for example cannot claim US unemployment benefits), there is not much legal maneuvering you can do with a one-person partnership, etc.
Your venture is a whole other beast. First, keep in mind that you need to foreign-qualify your LLC in every state where you do business. It's hard to know whether you will need to foreign-qualify since you did not provide much information as to the nature of your venture, but for example accepting orders in New York means you do business there and to foreign-qualify in NY will run you over $1,000 (and if you are transacting 100% virtually, I have a hard time understanding why you need a US-based LLC). Second, if you plan to raise capital or incentivize your talent via equity, it is much easier to do so with a corporation than with an LLC. Third, there are tax implications pertaining to drawing partner distributions vs. shareholder equity, etc.
As you can see, there are no quick answers and you need to provide much more detail about your plans. In any event, I really recommend that you get a preliminary 1-hour consult with a lawyer and an accountant. If you feel that you don't need to go that far at this stage, then you probably don't need an LLC either.
To your other questions, LLC paperwork could not be easier. Book keeping is easy too, you can use quickbooks online ($17/month) or clearcheckbook.com (donation). Have an accountant show you how to reconcile your bank account once per month, and you are all set.