The thicker the filter and the lower the MERV value, the longer it can usually stay in place.

We’re a Canadian couple ....Driving over on your days off might lower your anxiety.Maybe stay overnight in a motel, get your hair cut there, eat in the restaurants.Get to know a few cities well, and get to know the neighborhoods there.Talk to a few realtors and shop in the local grocery stores.After a few trips, you will know where is not safe, and where is more safe than the not safe.Also once you cross the border 911 is the call code for help if you need it, but don't expect the Red Coated Mounties in their shiny brown boots. 

If they've been there longer than that I will generally do 1 coat (no color change).

Get thicker skin - if you can't ignore somebody hiding behind a computer, how will you react when confronted with some of the sorts of tenants that are out there?

You get the seller (usually a wholesaler) enthusiastically pushing a teardown on any investor who will listen to him, insisting that it's worth all kinds of money in the right hands, downplaying the renovation costs and time and pretending to all kinds of fixer knowledge by self-importantly throwing out things like, "You've just gotta skim coat that!"

I would do chain link ( powder coated)  or like Florida block and stucco. 

I've painted it and it's amazing what a fresh coat of paint will do.

Some of the areas can just be covered with a roller, but other darker areas can't and require multiple coats and if the area has a higher gloss paint (doors, closets), the entire area needs to be repainted for it to look normal. 

I think we just coated it with the oil they make for it. 

The boys do first coat rolling and I topcoat.