I'm curious to know your opinion about why Seal Beach and Rossmoor are such relative bargains given their proximity to the ocean and their great schools?  

If they do not open the letter it will come back to you sealed.

We have a strong military presence here (Navy Diver training, Navy Seals Academy, Tyndall Airforce  -top gun flight school) and our International Port is expanding though it's already the largest exporter of wood pellets to Europe and copper importing to the East Coast.I mention all that to drive home the point that this area is becoming more and more of a destination attraction with amenities that were never here before.

The only other reason he might not want to let you talk to the other investors is that he dosent want you to seal his pool of investors, but if this is true I still don't see why he would not let you talk to one or 2 of them.

Tile: Materials cost (tile, grout, backer board, sealers) + 7 per square foot for demo, board, tile, grout and seal.  

I find most of the smell is usually in the floor so sealing them gets rid of a huge part of the issue.

Had that too and the process was to dig up the line, chop the roots around it, sever the line in two places, r/r and seal.

EBBs also work better in buildings with well sealed (no drafts) and well insulated building envelopes.EBBs also need to be unobstructed (do not set the chesterfield or bed in front of the baseboard) and kept clean (vacuumed at least twice per year) to operate at their best.So, after that attempt at the basics of EBB convection heat, the short answer that your tenants will likely incur higher heating costs, some of it as a result of drafts in the building envelope and some from the manner in which they are operated.

I was thinking about filling with composite sheet rock, waiting for it to dry, and re-sealing with latex caulk ORFilling the crap out of it with Gorilla glue, waiting for it to dry, and then re-sealing with latex caulk. 

Windows, doors, rim joists, etc. can all be sealed pretty easily.