For others who may have this question. Do not use glue on liquid-tight conduit, compression fittings required for a watertight seal.
yes. When used outdoors the sunlight will eventually turn it brown so I used real cheap latex outdoor primer and that protects it from the UV
Yes, the outer diameter of the belled end is 2.375 inches.
Looks like maybe "Jwr" and "Chris" may be the same person? At any rate, TWIMC, I posted this for another answer but you can extrapolate from that your answer if you do a little math: "I believe it would have to be the OD of the plain NON-belled end. Because sch. 40 PVC has a thinner wall than sch. 80; 2" is the nominal ID; 2.375" is indeed the nominal OD for sch. 40; .375 / 2 = .1875" or 3/16" for the wall thickness, which is about right for sch. 40 conduit.....however, when I check the charts they show .154" as the MINIMUM wall thickness for sch. 40 conduit, so this seems to be a bit thicker than the minimum. At any rate, my math IS correct." So, the belled end must go over 2.375" OD, so that would roughly be the ID of the belled end + wall thickness .1875" = ABOUT ~2.5625" OD for the belled end. There, I did it for you. ;-)
You could probably get 10 or so in there, it won't be fun....
Technically, it could be used for a water supply, but that is far outside its intended use and goes against all of the testing and QC parameters. The PVC in conduit is formulated to be fire retardant and UV resistant (among other properties). It is NOT formulated to be safe for drinking water, therefore, there is a reasonable expectation it will not be safe to use for a household water supply Spend the money to do the job properly the first time and use PVC that is designed for supplying water safely. Your health and the health of your family is far more important than saving a few dollars and cutting corners.
4 would fit well
Go old school - buy a 12" roll of the cheapest aluminium foil down at the dollar store - cut in half and then string a 6" wide strip along the top of the pipe for the full length of the pipe. Unless you bury it over 18" down, even the cheapest kids metal detector should be able to fine it for you.