Pvc, Wirsbo, Copper, galvenized, pex, or Polyethylene
water pipe
Bend meter is a type of pipe which are bend may be sharply or 90 degree . In fluid mechanics we calculate the losses inside the pipe .in which losses are more.
That depends on the number of fixture units in the house. Usually, your county or city building inspector can show you how to count up fixture units according to the local building code. BUT . . . if you have a normal house with 2 toilets, a shower, a bathtub, and 3 sinks, you might need a 3/4-inch water service. In my town, the minimum size is 1-inch, so that if you add anything in future years, the meter and pipe will deliver sufficient flow at a good pressure. If your house is very large and there is an irrigation sprinkler system, then it might turn out that a 1-1/4-inch or even a 1-1/2-inch meter and pipe would be necessary.
what type of material the pipe is made out of.
Probably a regular energy meter that is meant for you to use in your house.
Deep water
Don't you have any type of building department near you that has some type of code book?
No, hard water is in the water, it is not caused by the type of pipe.
Teflon tape is good. There is now a teflon liguid sealer also. The old pipe sealer is still good. I used a piece of radio solder last year to seal a water meter joint when I lost the meter seal. Be inventive.
Hexagon
No. Most water meters are of the positive displacement type. They meter actual volume, and are pressure independent. Also note that water flow and pressure are not the same thing. You can have high flow with low pressure, and also low flow with high pressure, depending on the size of the pipe and/or openings (such as valves) and the pressure.
This is a sign of residue in the hot water pipes. i guess at your part of the world, you must be using corrosive type of water pipes. The heat in the water helps oxidization of the inside of pipe and when the same pipe is not used to transfer of water in the pipe, existing water in the pipe caused corrosion so when the tap is opened after a while, the water that comes out is brown. To avoid this, you need to use the tap more often to stop the brown build up inside the pipe.