You can already upload custom avatars if you configure it in StaffCP > Avatars
To have clean urls like that, you just go to StaffCP > General Settings and enabled "Friendly URLs".
But before doing that read over this and make sure everything is correct in order for it to work.
A module like that already exists, it's under a different name, but functionality is essentially the same, you can find that module here.
Alrgith, so from what I can see, the latest ban was because of "Ban Evasion", and the older one was something about "rude + keeps questioning rules + telling me I'm stupid and need to read the rules again when I highlighted the ruels he broke + claims it's not a rule."
V2 already has a module for making staff applications, it is called "Forms module" and it can be found in Nameless resources page.
Here is direct link: https://namelessmc.com/resources/resource/43-forms-module-for-200-pr7/