The distance from the road to the house can make a difference for two reasons:
- water running through a pipe has some friction, so when water is flowing, depending on the volume, speed, and diameter of the pipe will all affect what pressure losses you may have
- water pressure will change with elevation at about 0.43#/foot of elevation change. So, if you're actually downhill a bit, that water coming down the hill will have more pressure at your outlet simply because of gravity. Conversely, if it has to go up to your house, the pressure will drop accordingly (so it wouldn't be uncommon to have different pressures at the supply by the road and at the house). To ensure water gets to all of the homes up and over hills, the utility may need some fairly high pressures, and a PRV is then required per code (must be >=80psi in the home).
A PRV will have a maximum range over which it can work. If you have REALLY high pressure, depending on the PRV you select, you MIGHT need two in series to drop the pressure sequentially to a safe value, otherwise, having a secondary one isn't really much of a benefit. Exceed the range of one, and you may cause it to fail. Most people won't have that issue as their pressure isn't that high.
An ET won't last forever - eventually, the bladder will leak. They don't hold their pressure forever, either, so you should probably check it maybe annually and top it off if necessary. FWIW, the cap, if it has a good gasket in it, is the better seal than the Schrader valve in the tank. IOW, don't omit the cap and make sure it's tight.
A PRV creates a closed system. That means that when expansion occurs, it needs a place to go or it will leak out the weakest location. In a well maintained system without leaks, that generally (at least should be) is the safety T&P valve on the WH, but it could just as easily leak from a worn valve. Common ones are toilet fill valves, but any valve with a leak under high pressure can potentially relieve it before the T&P valve opens (which SHOULD be at 150psi...your gauge may not be well calibrated, or the valve might be a little weak).
To comply with federal guidelines, if your utility doesn't already have a check valve on your supply, they may be installing them, so that could then make your system closed, when it didn't beforehand, and require an ET.