Personally I've been streaming with moonlight/sunshine onto my steam deck instead of Steam's remote play. It's higher quality, lower latency, and it handles non-steam games. There's even a DeckyLoader plugin to make game tiles to make the streaming option look more integrated.

A couple of things to note if you go down that route:

• Youtube guides on setting up sunshine on windows are a few months out of date, you'll need to do some remajiggering to get it working

• Sunshine needs you to add a script to launch from a desktop shortcut if you want to boot in directly from the Steam Deck. Steam makes it easy to create desktop shortcuts, and you can toss them into a desktop folder specifically for said shortcuts to make it easier and clean.

For your other questions, I'm not familiar with any way to remotely unlock your PC. You can set it up to not require a login on waking up from sleep though. Also, when you stream the game via Moonlight/Sunshine the game doesn't automatically shut down.