2007 roo 23ss slide gasket repair

Looking for advice repairing slideout gasket on my roo.

1. Is Geocel 28127V Pro Flex Bright the right stuff to adhere this?

2. Recommendations on what to use to clean the fiberglass before I apply the sealant/caulk?

3. Do the entire seal or just the part that's worked it's way out?

Thanks in advance all.

JJ