Those are strong ideas! One thing players also do is just make a new User character, and introduce them as a switch-hitter who fills in temporarily with the crew while their PC is on the stack (this is common in Blades as well, which uses Incarceration as a potential outcome that can also take a PC out of the game for lengthy periods). Depending on how "hard" the GM and players like to play the system, it's possible to chew through PCs! This can be used to tell a generational story about the founding members of the crew and how the torch gets passed as they fade out of the story and get replaced by fresher blood. It's not necessary to play the game that way, you can certainly end a campaign with the same character you started with if you play them a bit more cautiously, but it's one way to do it.
One of my 'stretch goals' is to eventually have playbooks for Shades and Process, which would introduce official options for the other ideas you've mentioned. In the meantime, check out the Daemon if you want to see one example of this!
There's a lot of setting writing I need to do to flesh out the idea of Process in the setting, but it's definitely meant to be something you can adapt to your own ideas... and you definitely have some great ones! I'm glad the setting inspires!