What is a "LLC" how does it differ from a "INC"?

While I am not familiar with Florida's rules of civil procedure (assuming you would not be in federal court pro se in a matter like this), a party can generally order the deposition of any person likely to have knowledge relevant to the dispute, whether or not that person is actually a party to the lawsuit -- directly or indirectly, through their ownership of a business that is a party. If someone might know something relevant, they can generally be made to talk.

I know this is not responsive to your "LLC vs. corporation" question, but that one has a huge answer and doesn't seem on point to what you're really after. If you want to explore business entity types, I recommend findlaw.com, which has good resources on these things. With all respect, I should also say that it worries me that you are proceeding pro se with so little basic legal knowledge to guide you; I would kindly recommend you seek the services of a licensed attorney in your community.

LLC stands for Limited Liability Company. An LLC actually combines aspects of partnerships and corporations, so an LLC is less formal and more flexible than a typical corporation, yet offers protection as well as certain advantages that are much the same. For example, members cannot be found personally liable for company debts. Their assets are separate from the assets of the LLC so they cannot be seized. One of the advantages of an LLC is that taxation is based on the partnership model. Flow-through taxation is advantageous since members are only required to pay taxes on their earnings once instead of paying both corporate and individual taxes.

Once again, chslaw is absolutely correct as to the general theory.

One caveat -- the relevant laws vary by state, so for any given state, the terminology and the formation process might be slightly different.