You don't need a side badge to work. You do need a Sida clearance. Without that you legally can't go down the jetway to the aircraft prior to passenger boarding. There are several levels of a Sida clearance. The most basic let's you down that jetway and on the ramp in the shadow of your aircraft. That is what most pilots have. If it's revoked you can't work. The next level is to be badged for ramp access. Some airlines do this but most don't.

I wouldn't lose much sleep over it. Pay your fine if it comes and chalk it up as experience I guess.

You need to keep being contrite and get a lawyer fast. Talk to the union if you have one.

If you get your SIDA privilege revoked, you could very well be unemployed. As sailingfun mentioned, badge is irrelevant, but you most certainly do need SIDA privileges to be a 121 pilot.

I think any future employer would be somewhat understanding since TSA regs are so confusing and contradictory. It's not like you were deliberately doing something like smuggling unauthorized items through KCM.

Assuming you don't get fired. Usually this kind of thing doesn't make it to court, but if it does the consequences can be severe to your career or wallet (the fines are large, up to five digits).