I did some research on apartment buildings and found out that the value is determined by the cap rate.

This RE company says that they provide additional training and they want me to sign a contract to be an agent with them.  

You take a risk which could result in cancellation of your title insurance and complete loss of your real property without compensation in the event that a title issue regarding your real property arises.Contact your title insurance company to determine coverage and if your policy does cover transfers , and when or how.DOS - The transfer most likely will trigger the Due on Sale clause (DOS) - a detailed resource on Due on Sale you might want to read is: the-truth-about-getting-around-due-on-sale-clausesAlso, these threads might be worth reading:386043-bank-called-my-due-on-sale-clause183825-due-on-sale-clause-was-called-by-bank232247-due-on-sale-clauseThen, if you choose to proceed, at least you'll know what you getting into.

You need to check not only the lot usage percentage but yard requirements (side, front, rear) as well as floor area ratio or max square footage, max height, and possibly other things before really determining the size house which can be built.

Your job is to determine if the risk is worth it.If you are are just thinking out loud that you may want to sell in 5 years, given your own statements that it is making great cashflow for 5 years, then who cares? 

But my biggest concerns are:Will the current legal owner sign a grant deed to you?

I would be the one determining the property, fixing it up, finding a property manager, and everything else that would need to be done to rent it out. 

Agreed that you should certainly be speaking with an attorney you trust before signing anything related to this deal.

After determining your MAO for a property, when making an offer, do you through out your max and decline any counter offers, or do you start negotiating below your MAO?

Did you sign a personal note on them?