I was told I would be getting an email with instructions on where to send what documents. 

If you wire the funds, call the title company directly to get the wire instructions, don't trust that your agent will send them.

But you can use CPVC and PEX following proper manufacturing installation instructions.Thing about PEX and CPVC, you don't have to worry about getting pin hole leaks like you do with copper or galvanized steel pipes and installation is easier.PVC is fine was waste water and drain situations.

Bought a manufactured home that was half-rehabbed.

I have also had a window break twice due to what we believe were manufacturing defects.

Reviewed IRS 4562 instructions but it is not very clear.

Now we have an opportunity to buy a manufactured home.

Most manufactures wouldn't put more than a 15 year life span on a new system.I think you will do pretty well with the combined rebates and you should take advantage.

I have a couple of master's degrees, one in entomology, and one in instructional design. 

I don't know about that particular company, but I used to work for a modular home manufacturer in the Midwest called All American Homes.