You are the owner, The tenant just needs to know where to send the money each month, and who to make the check out to.3.

One of his investments is a 10 Unit Apartment Building.Gonna meet with him soon to “chat”.I have never purchased a Multi-Family before and don’t even know where to begin. 

You also have the possibility that something an happen where one of you need to sell or take your cash out early. 

Where if they were using those funds to dollar cost average in marketable securities, they could keep 100% of that capital deployed and be asset allocated optimally based upon their retirement horizon. 

Do you have a buyer's checklist or know where I can obtain one for due diligence on a residential single-family home?

Do you have a buyer's checklist or know where I can obtain one for due diligence on a residential single-family home?

Definitely depends on where they are and who your desired guest is.

Of course nobody knows where rates will be or IF they'll be lower, but something to keep in mind. 

I would like recommendations as where i should go to invest it.

I really like the deals where the equity capture is more than the amount of out of pocket.