I use metal ones on all of my properties, but plastic are available.

The plastics ones from Home Depot/Lowes tend to treat me well.  

It's nothing more than a metal or plastic box 18" square with a 2" or 3" hole off the side.

I get that you can resurface a nice bathtub, but can you paint a plastic one?

Asbestos was used in many materials throughout buildings - stucco; window putty; asbestos-cement shingles, pipes, and flues; pipe, duct, and vessel insulation; sheet vinyl flooring; drywall joint compound (so over much of the drywall surface); plaster; floor tile (all sizes); flooring, mirror, ceiling tile, and other mastics; roofing; plastic roof cement; roof coatings; acoustic ceiling texture; ceiling tile; and more.Lead-based paint coated with non-lead-based paint in good condition is less of an issue, as long as it is maintained, and is not damaged or disturbed, as by repair and renovation work, or deterioration.

But many floor company may do it incorrectly.The following is a correct procedure:(0) Remove cracked tiles and mortar under them.(1) Use tar paper or some plastic lining material to cover the crack on the foundation with some sort elastic glue.(2) After new tiles are laid, apply elastic caulk with matching color around them.

The ground under the plastic is clay.  

The space was heated, but cold air goes to the ground, which is where the water pipe was.Another thing to keep in mind is that PEX pipe is less likely to burst when it freezes, since it is plastic.

Is there a Plastic surround to the tub or Tiled walls aepid that rub?

It is really hard and definitely not plastic and does have real cement or grount in between.