Selling a house will eat up 8% or so of the equity in selling costs. 

There are many other factors to consider- looks like you haven't factored in Vacancy, repairs, CapEx, Property Management fees (once you move out as primary residence- unless you're willing to manage it yourself) which eats into your overall cost of Investment/ownership- from the numbers you gave it seems like you'd be at a negative cash flow if you factor all these in.

Yes, HOA has been increasing over the years and eating more of my cash flow.

Any major projects would eat through that 10k number very quickly.Other than that, it looks to me like you're conservative. 

We have since stopped since it was “eating” into our bottom line and it was never mentioned in the review.

We’ve probably all never lived not knowing if we’ll eat for the next day or two.

also if i'm saving 3-5k per unit, that would be 12-20k saved just for renovations, which eats up most of my entire budget... is it impractical to try to buy a 4plex with this much capitol?

It does eat into your cash flow though.

Tenant laws can eat your lunch and I bet a paycheck they'll never get better.

I always liked the saying "you can't eat equity".