Kitty faces, water based urethane is just that. Any paint store/home depot etc. will carry it.
I know from experience that insects can eat through polyethylene. I have heard that insects can get into the flutes of Coroplast and live there. This occured in Argentenia. I'd guess that any humid, insect-prone climate would have similar problems. I don't know about the insect resistance of Tyvek.
I'm not familiar with Hugh's system of sealing glass to back of the frame (Wally, do you mean like a high class "masking tape the framing package together"?) If so, I'm guessing that this is a stronger version of using the Lineco aluminum/paper tape for the same purpose?
I also don't know if insects could eat through Marvelseal. Since it's used in the food industry, I'd guess not but....
I'm not aware of there being any rigid standards for different framing systems to accomodate for different environments. It's more a matter of figuring out the problem (or potential problem), reviewing the literature, networking with others dealing with the same problems, seeing how various systems have held up over time, using the materials available to us, being on the look out for new materials, using cross-industrial solutions (e.g. the food industry, packaging industries,...) AND, most important, sharing that information in forums like this or publications.
Being in Canada, I had no idea of the problems that those in tropical climes face. So I learn a lot from Wally and Buddy. Hugh's metier is framing systems, so it's always an education to hear what he's working on.
Me, I'm currently working on a huge pressure mount project for WWI regimantal colors and, when I work out all the practical bugs, will share with you all, as it really is a very practical, safe and non-invasive (though time consuming!)method for mounting fragile flattish textiles.
Rebecca