I kegged a brett beer.

Am I going to have issues kegging others after this? I don't want to infect all my other beer.

I'd replace all of your gaskets and the O-ring on your keg, then clean and sanitize like a mad man. The stainless should clean up fine, but any rubber bits are too porous to ever be fully trustworthy.

Put a label on that keg, so that you can track whether it had an impact on your next brew.

Lines...yeah sure, keep them separate. Taps, disconnects? IDK. I mean you should be sanitizing them anyway. Sanitary is sanitary. I have reused cobra taps and disconnects with no problem, but I fully dissasmeble them and treat them with hot PBW and StarSan.

The only o-ring/poppet that should come in contact with the beer is the liquid side poppet. I would not really worry about the o-rings. If you are worried that much, you could autoclave sterilize them (in a pressure caner).

Everything can be cleaned and sanitized. But the plastic stuff should probably be kept separate, simply because it's not worth the cost to have any issues.

Anything metal can be heated in oven to sterilize, or soaked in bleach solution. (except I think you're not supposed to soak Stainless in bleach). But a good cleaning and sanitizing ought to fix most anything that can't go into the oven