Deck repair question

[bcurling]

Boat has a soft spot in the deck. I want to cut out the soft area with the skilsaw removing a generous amount so as to get into the good area. One question, three parts.
1. Which is the best skilsaw blade to use (number of teeth per inch etc)
2. Should the cut be made at a 45 degree angle so as to retain the replacement piece of plywood when placed in the void
3. Recommended type of epoxy/resin/cloth to finish with

Thanks for the help.