R 3.4 Armaflex provides a table for all their pipe insulation at https://www.armacell.us/fileadmin/user_upload/Reference_Sheets_INS/AP_ArmaFlex_Tolerances_and_R_Values.EN.US.2017.pdf
it can be used on hot water lines with no problems, I have them on my cold and hot water lines that run thru my crawl space and have had no issues with them. The issue is outside weather may affect the rubber (Dry out) and the sealing tape causing it to coming loose after a period of time. If running from a outside boiler I would wrap it with a tape such as gorilla tape to keep the insulation from breaking down over time in the outside elements. Hopefully this helps you.
Immediately. The contact adhesive is immediate and there is no contact between the insulation and the coolant which is within a closed pipe system.
Yes, it will help a little. That is probably hammering. You should also secure the pipes with strapping after adding the insulation to restrict the movement of the pipes when cold water from the street comes in contact with the warmer water at ambient temperature that is already in the pipes. You might need to add anti-hammering to address completely.
Yes, but to protect from UV and bird attacks (they attack their reflection when you use aluminum pipe wrap tape) I recommend you wrap it in a rubberized vinyl tape. I used a white 3" wide tape that I applied lengthwise and was able to apply first to the top of the pipe insulation and then added a second piece lengthwise along the top which provided a 1/2" lap seam for the tape. Vinyl tape holds best to vinyl tape. I also did a radial wrap around the insulation at the 6' seams to help the tape seams hold their integrity. Worked great. See ProTapes Pro 603 Rubber Pipe Wrap Tape with PVC Backing, 10 mil Thick, 100' Length x 3" Width, White
it is usually 3/8" or 1/2" thick. You should see it in the product description. Don't confuse with pipe size. For example, a 1/2" by 6' rubber pipe wrap has a 1/2" thick wall but you would need to check the description further to see if it is for 3/8", 1/2" or 3/4" pipe diameter. A 3/8" by 6' rubber pipe wrap would have a 3/8" thick wall but is not commonly stocked as it's 2.6 R Value doesn't meet the recommended R value minimum of R3.
It's made of flexible foam rubber so I wouldn't think paint would last on it for very long.
This product is ideal for attics and un-insulated wall cavities (like garage walls). If your wall will have fiber glass batts or blown in insulation, that should suffice to prevent the pipes from contacting each other. If its an un-insulated wall then this item will be ideal. You can also look into an item like https://www.homedepot.com/p/Oatey-3-4-in-x-10-ft-Plastic-Hanger-Strap-33529/301505503 to anchor the pipe so there is minimal movement.
Technically that would be the only reason to use it, unless you have some very cold conditions inside.
yes, but you'll need to need to translate PVC pipe OD from the Copper pipe OD. A 1/2" PVC pipe would more likely be equivalent to 3/4" copper OD. You should do a fit test in the store befor purchase. If you are using for an in-ground sprinkler system, you'll still need to evacuate the PVC pipes.