That being said, I think it's just a common sense to avoid pitfalls to the extend possible and not give anyone, especially unscrupulous, unethical buyers and some overzealous gov attorneys a pretext to fine me into bankruptcy and portray to public as a "bad guy" (so they can avoid going after real bad, big guys that lobby and hire them for their own nefarious purposes).

That's just common sense.  

haha I mean I know that its an extremely popular avenue but I also know that real estate is constantly changing hands.

Two of the biggest challenges I face are that I’m not very liquid at the moment, and the Seattle area is extremely expensive.

Another case where common sense isn't so common.My $0.02 ...

I do pretty much like more SD than SA, but as you asked, the money that I have to invest it aint that much, goes between 30-40K to start and will be definitely for long term, as I said, I´m a beginner in this business in the US, as commons says I´m at the baby steps stage right now.

The common feedback I hear typically revolves around your accounting preference. 

No one will ever be 100% accurate with a spreadsheet, but I have to say that these numbers are... extremely optimistic.

Rent control in the bay area can be extreme as many areas have rent control in excess of the state mandated rent controlIn general experience RE investors are not choosing to add a single ADU in single family zoned areas.  

@Craig Oram this is a common issue.