i don’t understand. Do I need to be current on the 172 or not??

you need to be current on something. Nobody is going to hire you if you haven't flown in 18 years. You are just too much of a liability.

Prove that someone with insurance is willing to let you fly a plane. Either a rental or a friend.

Choice between Horizon and SkyWest?
 

Currently working as CFI/I and 135 Pilatus pilot towards ATP mins. Have a guaranteed class date with Horizon (Pilot Development Program) upon reaching ATP mins, and a guaranteed interview with SkyWest (cadet program). Based in the PNW, and am going to stay here. Which airline should I take, assuming I’m offered a job at SkyWest also?

Go with the first airline that can get you into class. Fly a ton and try to move on to your career goals as quick as you can.

I would recommend what ever company has the base you’re currently residing. Living in base allows you to pick up extra flying, and you’ll still have a better QOL then commuting.

The better question is how backed up training is for both companies. If you have to wait 6 months longer for one compared to the other, you might want to adjust your priorities in life. I’ve recently moved to live in base. Once I’m senior enough to live in my base of choice at my current company I’ll move again. I have a significant other who’s been willing to make those type of sacrifices with me, very lucky.

Moving all around the lower 48 for a regional?
To each his own I guess .
Not something I would do , not for a regional.

In theory moving once to live in base for a regional you work for isn’t a bad idea at all. Regionals tend to have all the crappy schedules(& pay). Living in base allows for a better QOL. Imagine commuting the day before and after a 4 day(especially during the last month or 2). Being on reserve while living out of base isn’t ideal. No thank you.

It’s not that moving to base is a bad idea. It’s moving multiple times for a regional base that is a bad idea.