Any suggestions not on how to put back but to reseal with that putty looking crap they had around the vent? What to use, how to get it in the correct place etc? Any help or advice be appreciated.

 

3M has sealing strips that work well for this application.

 

You can also get a white or grey strip calk version in the plumbing sections at a local Lowes or Home Depot. I believe the original calk was really loaded on on the surfaces immediately adjacent to the opening in the kick panel area down there.