The best way to prevent unnecessary repairs is to check in on your tenants regularly.  

I have a duplex that the gutter gets clogged up if you don't clean it once or twice a year.

There's a lot of knowledgeable folks to learn from and I'm also happy to share the mistakes I've made to prevent it from happening to others.

I don't want to clog up this post with details but if you want to hear them then pm work any questions. 

Any suggestions on how to prevent UD tenants from trashing the place?

If so, would that prevent me from taking out another HELOC after I paid it back?

The CC&R clearly prevents it along with an acknowledgement of the rules when a tenant signs up.  

Have you looked into whether this will prevent you from taking a 3.5% down loan in the future? 

Sell the lead to a real wholesaler who will pay you a finders fee if you don't have time to learn to do it yourself.Since a friend is involved I would do a double close to prevent him from finding out how much you made him overpay for the property.

Then using a long-nap roller, keeping a wet edge as you're painting to prevent overlap lines, and keeping the shingles just ever-so-slightly damp.