I understand they are usually lengthy in the purchase process, and the owner happened to be there when I did my inspection and told me what the other offer on the house was. 

Particularly since Zillow removes photos as soon as a listing is sold, leaving the interior a mystery unless I take lengthy notes before sale...

Investing with a friend or family member is a great way to get in the game, because the biggest barrier to entry to buy and hold real estate is the down payment requirements.So not a problem going into business with him, but you need to have some LENGTHY talks about expectations to make sure there are no surprises or hurt feelings down the road.  

The absence of a rent increase for 6 years, frankly, is something that your relative should have observed based on the cash flow he had been receiving from the property over that lengthy period of time. 

Either way, I've spoken to a couple of other resources that have said it is often a lengthy process.

I feel like that could open me up to a ton of potential problems, such as them deciding not to pay the rent, going through a lengthy eviction process, a judge siding with the occupant due to their time in the property and community.  

Thankfully, I did not have to go through the foreclosure process (it can be very lengthy) as she was the one who bought it from the bank and resold one of the 9 to us.

The last thing you want is to make this your business model and then find out their are illegal or there is a lengthy long expensive process to be approved.   

You question about loan length is a different issue.

before proceeding with a potentially lengthy and costly eviction.