Acquisition fees and asset mgt fees keep the engine running from the beginning thru the hold period, the real money is made by the GP at sale or some portion at refinance / supplemental loan when property renovations are complete / value optimized. 

I don't want a generic postcard.

However, I want to keep that going and at the same time establish passive income through multiple streams to supplement my retirement.

Should we put down a 20% deposit for our first home, or should we put down a smaller deposit and use the leftover cash to pay for an ADU that will generate supplemental income?

No I wouldnt I dont over pay knowingly ever but for someone who wants to supplement their retirement with out having to deal with houses all over the place over paying for the house next door might just work for them.

Not a generic office line, a cell phone.

You can supplement your income with representing buyers and sellers while working on investing.  

I'm from Kansas City, MO and I'm interested in learning about real estate investing for the purpose of getting some supplemental passive income.

I am currently a business owner of a sales and marketing company looking to earn supplemental income via a buy and hold portfolio of residential homes.

Are the online templates what people typically use, or do most investors have an attorney draft at least their first one?