Schwinn Gtx3

This is my Schwinn gtx3 that I picked up at Dicks for around $200 about 6 years ago before I knew anything about bikes. I’d like to keep it around for neighborhood rides and rail trails. Pretty much daily riding that I don’t want to do on my hardtail Mtb. Looking at doing very limited upgrades and want to make sure it will all work together.

1. Convert to 1x system. Front derailleur and shifter already gone (frustration induced binning). I’m 99% sure it’s a square taper BB so I’m assuming a cheap crank with narrow wide would work here? Probably 32 or 34T. Probably going to keep it a 1×7 as it’s a freewheel and I’m not looking to replace that to get a bigger cassette.

Please correct me if wrong.

1. Rear shifter. I absolutely hate the rotating shifter. I’d like to change to a trigger style. Nothing fancy. I’m a little lost on finding something that pairs with the existing Altus derailleur. Point me in the direction of what to get please.

The rear shifts and indexes quite well so not needing to change that anytime soon, just the shifter. Probably a new chain as well.

Any help would be appreciated!