You will learn a lot fast by reading the articles, listening to the BP Podcast (Nobody formally sells anything on any episode) and reading and interacting in these forums.

Many folks try and use these numbers as evidence of FMV but they are not going to be as accurate as a formal appraisal or even a CMA or BPO.

In other words I stumbled on them by accident and neither required any formalities.

If it's a close friends with high trust, an LP has less formalities to deal with.- there are additional costs associated with having an LLC (at least in California where I am)As to your comment on holding the multiple properties under one LLCs, I think that would be fine if you are the sole owner of these properties, but since you are looking to get into bigger properties, it may be worthwhile to just start with a new entity. 

They probably have no formal lease but it's implied by the fact that he's most likely been there a while.  

to a formal business partner or other agreements within the entity should not be a problem, in my OPINION.

Figure out these terms and then of course talk to an attorney to formalize the LLC, joint venture, or whatever legal entity you end up choosing.

One contractor said 45k with no itemized list or formal proposal.

I have already posted a question or two in a different thread but wanted to formally introduce myself here.I am obviously new here as well as to Real Estate Investing.

For ten years, I've run this business without formally evicting someone.