sounds like they make loans to new clients  flippers etc.. then investors buy the notes  ( probably a lot of fractionlized notes) and therefor you need a servicing company.. they are DRE licensed according to the website and the CA DRE has pretty substantial guidances on the brokers doing these loans..  5% for that type of servicing just probably covers the cost to actually do fractionalized loan servicing. 

Is there a website or other source of information where I could start to get some basic knowledge on the US housing market rules and tax laws? 

@Jayden BoysunIn order of priority:I would change my privacy settings so that I don't list how much money I have with my full name on a searchable website.

They have become very unresponsive and after multiple requests for them to update me or their website, I moved to a new PM. 

These sellers are typically opposed to having a realtor on either side of the transaction, so I would recommend you do all your homework on the bakc end by looking the property up on the county website to search for liens (yes always do a lien search) when purchasing a property especially FSBO. 

Go on the school website, go to a Starbucks and ask a student.

We have a Carrot website which is designed to generate traffic to your page and has spots for leads to input their info.

Are there any investors that use this website and could give me some insight pros/cons.

Check back taxes on the county website, Use a BPO agent to get some current pictures of the property.  

@Jorge CastroI checked that ViveDeLasRentas.com website and I'm not exactly impressed.