1. Liquidnails (Make sure you get the right kind for Foam, there are a few different ones)
2. Hot Knife Cutter (A box cutter could work but it's more likely to take some chunks off)
3. Around 180 grit sand paper.
4-5. I would paint it before you seal it. Put a couple layers of Gesso on it (It's a white goopy paint used as a base). After that, you can use fiberglass resin to harden it (Make sure you use a mask and gloves when using resin though). After the resin, sand it again, then add a final paint job. An acrylic paint should be fine.