Work with a broker who has access to a large variety is going to help you find an appropriate option for your situation vs a direct lender who can only sell you their limited product set. 

We lived in it as a single family residence and over the years of things that looked like they had been renovated started failing… we realized the owner before seemed to have a slap it together cheaply himself mentality.

If you find someone that seems to know a lot of people needing your services, wouldn’t it make sense to focus more resources on them?

I’ve learned to start the permitting process early and keep a close eye on inspection timelines to avoid bottlenecks.It can be difficult to find contractors who are not only skilled but also reliable and available when you need them.

I'd recommend David Green's book on the topic: https://www.amazon.com/Buy-Rehab-Rent-Refinance-Repeat/dp/B0...I also did a long live stream on it a while back that you might find helpful: 

I am mostly interested in investing in long term, single family, rental properties.

If you find proof that a plumber flagged this as a bigger issue, you could have a case that the seller was aware but didn't disclose it.Best of luck! 

I'd like to rent it as much as possible and leave a few weeks during the year to stay there with family. 

If you can't find what you're looking for, try the Bigger Pockets Fileplace.

Does it make any difference if capital is coming from friends/family versus "strangers?"