Once you have a foundational understanding, you can refine your knowledge through blogs or forums that address specific topics.You should also find a real estate investors group where you can network and learn from seasoned pros as well as newer investors.

My questions are 1) Is it better to get a "separate" address or should I ask for Unit A (main house) and Unit B (ADU)?

I stand by my statement, and based on the few details provided here, it's more than just likely this space would not be a fit for a national restaurant tenant (either as franchisee or corporate signed deal). $1 psf/mo NNN ($12 psf/yr) NNN speaks volumes about the location from a national restaurant chain perspective. 

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

I emailed the contact email address to ask questions and they were very quick to reply. 

Feel free to message me for some more details! 

Buyer decides to represent himself, buyer requests more details about a condo on RedFin, gets contacted by listing agent, LA and buyer meet at condo and do a walkthrough, buyer says where do I submit my offer, LA and broker both state your offer won’t be accepted unless you’re represented by a realtor, broker says you can use LA, buyer declines offer and says “I’ll have my realtor be in contact with you.

There are various services that provide sale data other than the MLS however many do not have as detailed information as the MLS. 

If something absolutely must be done immediately, do the minimum to make it safe and functional and then remodel once it's vacant.What you are possibly missing is the potential for problems in this situation:Jobs always take longer than planned, sometimes much longer.Fixing one problem often uncovers others which must now be addressed.

You should contact them directly as I do not know all of the details for each.