If you submit an LOI and then check out the property and don't want to progress any further then all you have to do is tell the broker.

Advance on best ways to get my license/find a broker 3.

I brokered 10 million last year of these 2-4 units.

Prior to doing your calculations, I would talk to a mortgage broker to determine what your monthly out of pocket cost would be for a commercial loan with the mortgage you're looking to take on.

If you are getting ready to list and sell, you need a real estate broker that knows the market and can advise you on the expectations for condition and finish level in your area, not a partner.

I can introduce you to a few brokers in that area who have multifamily units and/or get you MLS access. 

BTW, if you ever use a broker, make sure to include the disclaimer that no commission is due on any seller concession.  

He makes goods money and so do I but I am a broker and work contract roles so my stability is lacking right now.

Also, you might reach out to a commercial broker in the area and see if they can give you the prevailing cap rate for the area and size/class of property, with that you might be about to get a feel for what other properties in the area are trading at and give you some more leverage for negotiating.

What complicates matters for me is I am licensed in California, and my employing broker doesn't allow me to do my own deals :( Since I can't represent myself as an agent, I thought about using the dual agency method.