Even if you only averaged 2.8% appreciation annually, which if you've had it 20 years I have no clue how that's true given prices have well more than doubled in that time, youre skipping over the fact that you have been benefiting from that appreciation on the ENTIRE house, not just the % you paid for.  

Residential property rental: Could this be a scalable and profitable approach, or is it too risky?

Now I'd like to sell.I originally wanted to put apartments or several houses, but not anymore, cuz I want to do more hiking, biking, and Netflix-ing, and less scheming.So do I sell as a rental property or as land?

If you are looking at Property Values, use zillow.com, that is what we use to fact check properties values. 

I do emphasize on showing that my 1800 property is not going to magically become modern. 

Quote from @Paul Whitehurst: Many will tell you to borrow money from Property A to purchase Property B, but that's known as over-leveraging and not recommended for a newer investor.

I’m a Realtor and property manager in Austin and happy to help in this area!

Depends on which property you pull equity from.

Basically - I want a PM who keeps the property in good shape and occupied to get paid, and a PM who is either bad at maintaining properties and finding good tenants, or just really unlucky, to not get paid.- PM charges 8% of rent, which escalates to 10% if the property exceeds 95% occupancy with rent collection. - PM charges minimal fees.- PM is contractually obligated to perform annual maintenance/inspection to keep property in top shape. - PM provides a cash based accounting report every month, for every unit under management, that clearly labels all rent, all expenses, including management fees, and the net directly ties to the amount of money deposited into my bank account.- PM is a licensed handyman, or has them on staff, and takes care of most unit turn work at a reasonable rate. - PM has no breakup/termination fee- PM does not take project management fees, except on large or complicated CapEx projects exceeding $5,000. 

Freddie Mac only offers financing for single properties they do not offer 'Portfolio loans" meaning bundle them all into one loan.