Depends on the lender and what risk factors they perceive.You state that financing will be 75% ltv, 5-10 yr fixed, 25 yr am.

You will need to learn how to run comps, figure out what rents are in the area and build connections to PM's, GC's, etc. 

If you have a small multifamily (let’s say 4-family apartment) that has a main common entry door into the building, are you supposed to change the lock whenever any tenant moves and then give all the tenants the new key?

I am currently active duty military and looking for investment options for the property to create a passive income and build wealth.

I have a very picturesque property that I have thought of using as an Airbnb type situation, initially with a building not is use....however I am on a creek, with a little dock.

If you just sold the property after building equity then put that money in the S&P 500 you make way more money.

It's building up equity over the long haul with built-in equity from buying right, appreciation and principal paydown that really builds wealth in real estate. 

I have several clients who flip and a diverse portfolio of buildings.

Consider factors such as location, property condition, future development plans in the area, and your long-term goals.Remember, patience and persistence are key.

You will miss out on building relationships with agents that may be able to bring you deals.