Home Depot offers multiple options when it comes to pipe. This particular piece is a 2ft length and is typically used in a repair situation. Your local store typically stocks ten foot lengths.
CPVC 3/4 inch pipe can also be bought in 10 ft. lengths at your local store.
Yes, but I would be using sunlight resistant grey plastic conduit or white pvc myself.
Yes. Home Depot instructions for installing a TPRV on a water heater say to use CPVC: https://www.homedepot.com/c/ah/pressure-relief-valve-installation/9ba683603be9fa5395fab909404dfcb
For additional information please contact our Technical Services Department at 800-438-6091.
Not advisable. Check with local building inspector, but galvanized steel or PEX is likely a better choice: http://facilitymanagement.com/piping-material-plumbing/ "Galvanized pipes are typically used in the following applications: Water supply lines Outdoor applications Underground applications" https://apolloflow.org/faqs "Can I use PEX pipe outside? Yes. However, it MUST be protected from direct and indirect sunlight. PEX pipe will start to become brittle and crack with continued exposure to sunlight."
The discharge line from the T&P relief valve is generally the same size as the valve outlet. The water heater manufacturer's recommendations should be followed regarding T&P relief valve size, assembly and installation.
No. "Chlorinated polyvinyl chloride pipes (CPVC) are made from PVC that has extra chlorine added to the material. It carries all of the benefits of PVC with added durability. CPVC will not degrade with hot water exposure and is safe for drinking water. It is slightly more expensive than PVC, however, and will split if allowed to freeze." http://facilitymanagement.com/piping-material-plumbing/
Find out if it's a leak or condensation. If it's a leak: https://www.homedepot.com/c/ah/how-to-fix-a-leaky-pipe/9ba683603be9fa5395fab90a6c87071 If it's condensation, insulate it: https://www.homedepot.com/s/pipe%2520insulation?NCNI-5
Ford, This particular pipe is for water supply only. We recommend you use our Schedule 40 PVC pipe for drainage applications.