28 years old, had big success in stock market. RE advice needed.

[Brian Peter Griffiths]

Here is my story sorry it is long. Scroll to the end for the TLDR.

5 years ago I was working 15 hours a day, 6 days a week managing a restaurant in the DC area. I became obsessed with frugality and the Stock Market during this time. At 22 years old it was depressing to think I might be managing that restaurant for the rest of my life. So I quit my job. I got my TEFL teaching certificate and got a job at a University in central China. I took an annual pay cut of about 50% but my working time was reduced by a factor of ten. From about 70 hours a week(including commute) down to around 3-6 hours a week. So some readers may have figured out that I earned a massive hourly wage increase, from 18 dollars an hour to more like 40-60 based on the school. Also had free accommodation, 6 months paid vacation 3 winter and 3 summer so needless to say I traveled a lot, been to 14 countries. I used all that free time to attempt businesses and be involved in existing businesses, gained a wealth of experience. I was able to save about 70% of my earnings during those 4 years in China. 

TLDL

With frugality and intelligent investing I managed to grow 8k to 106k in 5 years(about 30k tied up in an IRA). I just returned to the United States 12 days ago and have been wondering what my options might be for my roughly 75k in liquid assets. I have decided my first goal will be to replace the previous income I was getting(about $800/month) with passive rental income. I am looking at property in Maryland, W. VA, and VA. Looking for Duplexes and Triplexes in my price range.

QUESTION

if my goal is $800 a month of profit, is that doable with the 75k? Should I try to spread out my money or go for a single "turnkey"(not sure if i am using that correctly) property? Should I try to pay down rental mortgages aggressively that way I can drastically decrease my costs? What about down payments?

Anyway thank you to anyone who took the time to read this and a special thank you to anyone who takes the time to respond. This is my first time posting something to BiggerPockets.