What are the biggest pitfalls I should look out for? 

Why do you care if a crazy person on the internet calls you a scammer?

It's the biggest unit of the 4 with the highest rent.What can I expect with this tenent?   

This was during the biggest run up in RE prices since FOREVER.

I have read on the internet that some parts are and some parts aren't safe.

My biggest fear is that if I ever were to quit my job, I would no longer be able to invest in more real estate (not sure if I would qualify for loans as easily). 

One of the biggest red flags I have as a lender (who lends my own money as well as secondary market loan) is when a rookie tells me there goal is to buy 10, 20, whatever properties in the next year. my next question is how many do you own currently?

Ones of the biggest was that we had to completely replace all the old electric, luckily we were able to save in other areas of our budget to offset most of the costs but not all of them.

Then moved out and we're sharing another house hack with less than $200 out of pocket monthly for utilities and internet while using 3 bedrooms and a bonus room for ourselves.

My biggest tip here is work with the smaller companies.