Use Teflon tape with a little pipe dope. If you don't ever have to take apart again then you can use glue which you are calling cement
No, do not use glue. Use teflon tape or pipe dope on the threads. You should also make sure you always put the male PVC thread into the female metal thread. If you do it the other way you will tend to split the PVC fitting when you tighten the threads.
It depends on the size of PVC. For smaller PVC you can buy fittings that glue onto the PVC and allow a thread x barb fitting to be installed. For larger pipe you should get a brass compression fitting that clamps down on the PVC and adapts to a thread x barb fitting.
Pipe dope and/or teflon tape
If you are screwing in -- yes -- If not -- you do not use pipe dope
No PVC cement can not be used on cpvc pipe. Cpvc and PVC pipe have different chemical compositions so a cement made for one will not work for the other. The process of joining plastic piping together is called solvent welding and the use of the wrong formulation will result in an inferior weld
No, it won't stick to most PVC. Oatey's Transition Cement and most epoxies will work IF the PVC is dry.
C x M adapter C x F adapter PVC x F adapter PVC x M adapter or Thread if your really using "pipe" in lieu of "tubing"
There is no special PVC pipe. CPVC can be used for hot water applications or in my opinion just use PEX pipe.
Yes, that can be done. Just get the correct connector to use when connecting the PVC to the metal box.
No, there is no suitable adhesive. These must both have threaded endings and be mechanically attached or use something like a 'Sharkbite'
If the hole is clear of the concrete get a little bit of pipe 25mm or an inch and cut it along the length so that you have a ring that opens up. Get some PVC primer and PVC solvent cement . use the primer to clean the outside of the pipe with the hole in it and the inside of the patch. put solvent cement on the pipe around where the patch is going. stretch the ring so it opens up and covers the hole and hold it in place. you can do this with a suitable hose clamp. wait a couple of hours before use. if you can reach the inside of the pipe you can use a similar procedure,
If the brass threaded nipple is a male end and the PVC side is a female end, wrapping thread tape around the nipple and then screwing it into the female PVC end will provide a secure and watertight connection.