NON-RECOURSE is the key word here for the mortgage and yes, you have to pay UBIT or UDFI on the rental income that is financed but it really isn't a big deal.

I adviced him to use a cash for keys method.. let's see which happens first

Whether you are into wholesaling, long term value add residential properties, house hacking, STR properties, flips, or turn key properties.

If so then passive rather than active investing will be key and that takes you back to the classes of passive opportunities using them to pay bills while you develop your next "thing".

By what are those key things that a first time landlord should know.

From everything I've read and heard, having the proper systems set up when first starting out is key.

These are actually key factors why we choose to live in that area.

It is difficult to have an efficient system at the beginning but if you have agents that you can trust and they deliver a good service, I believe it will be worth it.

You bought where the numbers made sense and you made it work.You know how many people are sitting at their key boards stuck in analysis paralysis trying to control every single aspect in a deal and making every excuse not to go through with it.Once again I commend you in your actions.  

Having a supportive wife is key :).