Over time, as you gain more experience and capital, you can consider expanding into multifamily properties once you've built up a solid foundation in real estate investing. 

@Polat CaglayanI've never seen a formula but here is a general rule of thumb for multifamily:The class of an apartment refers to the quality of the building, which can be determined by a number of factors, including age, location, and condition: Class A: These are the highest quality apartments, typically built within the last 15 years.

Does it look like a modern-ish apartment with breezeways and internal stairs, or is it built like a roadside motel with long walk ways along the front.  

I built a 12-door portfolio in Detroit, and the process wasn’t easy, but it’s one of the few markets where BRRRR and strong cash flow still work—if you have the right setup.A Few Thoughts on Your Questions:1.

The list goes on.For mission-critical items, you want quality, not cheap.

Since I have been using Padsplit for my first 3 investment properties I don't have the skills built yet for marketing or rent collection. 

Certain cap items is fixed or pretty close to fixed whether you are buying a $60K house vs. a $500K house in the same market. 

You missed an important item: Depending on how a person does #1 or #2, it could get them: A fast-pass to the "Principles Office" for "bullying" and now there sitting in "detention".... 

Built in microwave, I would not.

I'll Google those items and see what I find.