What Hershel describes is frequently called "lead-lag" operation.
My advice is either to get an integrated magic box:
or to hire an electrician. Pump controls are no joke, and if you do it
wrong, the cost to repair pump motors is pretty high. Not to mention,
when the water goes out, people just love to complain.
As to how the alternating circuits actually work, I have no idea. I've
seen the little doodads inside the control panels, but don't know how
they work. I presume that they are solid state.
I have however seen it set up so that a mechanical timer alternated the
relay that was energized to start the pump. This only alternated the
pumps, and didn't provide lead-lag. This was a nasty hack though.
As far as the cut-on/cutoff pressure, a good cut on is 45 psi, cutoff
at 70 psi. If you had a lead lag setup you could start the second pump
at 30 or 35 psi.
However, if the neighborhood has a lot of relief, you might get low
pressure above the pressure tank. I can't imagine a 10 home
neighborhood having that much relief though.