Nix / NixOS

Hi all Nix experts,

I recently started using nix to manage my dev environment on my immutable distro, and I need some help.

I was wondering if I am using a large package like TexLiveFull, how to make sure nix don't delete large packages after I close the shell? I also don't want this package to be available in my global environment, as I don't need to use it outside vscode.

Another question is how to keep my packages up-to-date. I don't do serious development work, thus I typically perfer my package and dev-tools to be on the latest version. I prefer to have a little management of this as possible. Ideally, every time I start up a nix shell, the package manager will grab the latest version of the package if possible without requiring additional interaction from me. Is this possible?

Finally, is there any way to bubblewrap programs installed by nix to only access the file within the starting path of the shell? I don't imagine this is possible, but it would definitely be nice if nix has some security feature like this.

Thanks in advance for your help! I understand parts of this post might be ridiculous. I am still new to nix. Please correct me if I am not using nix in the "correct" way.