Even within the topic of 'investing in the stock market' you will find a range of sub-segments, like day-trading, swing-trading, or low-involvement long-term investing. 

I want to be more closely involved in the process to learn as much as possIble and be able to see it firsthand.

Often there are many people involved, siblings in other states or a child or spouse they want to consult with before making a decision.

A 16 unit multifamily can qualify for a 35 year fixed rate loan under the HUD 223(f) loan program, however the fixed soft costs involved with that program generally are not economical for a request of that size.

I do almost all my own work, even if it involves sweating pipes and gluing drains.

You will need to involve tradesmen to run the electric and set up the panels and water lines so it could get spendy so you'd have to run the numbers locally to figure out if it's worth it.

My brother, who lives in Florida, really wants to get involved in real estate but he does not have any money and does not own a home yet.

Start by getting as involved in real estate as you can by either switching professions to something like working for a property management company, home inspections company,  mortgage broker, or becoming a real estate agent, etc. or do one of these on the side in addition to your current job while starting to invest in real estate. 

There are a lot in South Florida and another great resource to connect with investors and others involved in real estate.

Sorry, but it’s quite simple......the buyer was denied financing (doesn’t matter why) and notified you within the required period....as per the contract you have to return their EM.