Thanks again for the info. I think I'll look into the blue/pink foam and nothing else.
Didn't know about the expanded foam, are the termites drawn toward that? If so that might help explain an area where they used that near the wood on my basement staircase had termite damage. That's a whole other story, but for now, luckily they are gone.
As for the PT and the nails, I've actually been using decking screws on most of this. I'm not sure what they are coated with, but will check. The ones I'm using are a brownish color with a star head and drive very nicely into the 100yr old lumber. I have a hard time getting a framing gun to sink nails into the old framing...
Thanks again for the info. Gives me a lot to think about!!