"How much hot water must be flowing before the tankless water heater turns on?"
The minimum flow to operate these tankless water heaters is 0.66gpm.

"What is the minimum amount of water pressure needed for these to operate?"
These units require a consistent 14psi or better water pressure to operate.

"Will an instantaneous water heater save me money on my utility bills?"
Yes, in most applications you will see a savings. There are some variables that could reduce the amount you save. One example is you will not run out of hot water, so longer showers could cut into your savings. Also, the cost of electricity, propane and natural gas in your area will affect the amount of money saved. The higher the cost for the energy type used to heat your water, the quicker you will recover the higher initial cost of installing a tankless versus tank style water heater.

Positives:

You will never run out of hot water. "You want an hour long shower? No problem!"
Electric units can be installed at the point of use.
You're not paying energy costs to heat water 24 hours a day.
They're easy to install.
Our electric units don't require a T&P valve. (No tank!)
Installing a tankless water heater will indeed be a bonus to the environment (why should we choose wastefulness when we're talking about finite natural resources)?

Negatives:

They all need a minimum flow rate & pressure to turn on.
The faster water flows through them, the lower the temperature rise. So, if you expect to take a shower while the clothes washer is running, you will need to select a unit sized to your hot water flow requirements. (Gas units handle this a little better than electric models)
Electric units need heavy gauge wire. Example: the 9.5kw must have 8ga wire and a 50amp breaker.
Gas units need a much larger, special flue pipe and larger gas supply than a conventional water heater.
At times they can produce very hot water. It's easier to get scalded.
Gas units are more complicated than a conventional water heater.
With some brands, parts are hard to find (not a negative if you originally purchase from us, as we like to carry parts for the units that we sell).

Summary:
Tankless water heaters have their place. They're not "the answer" to every hot water need, but if they're used correctly they can be the solution to many of them.

"What water pressure is needed for supplying hot water to upper floors?"
To supply water to upper floors, you'll need an additional 0.44psi/ft of water pressure. Basically, for every one vertical foot, you'll need an additional 0.44psi of water pressure.

"What water pressure is recommended for well water?"
Well water systems should be set at a range of 50-60psi.

"What are the best reasons to install a Scale Inhibitor System?"
The system inhibits scale build-up and protects the piping from corrosion, which helps maintain efficiency and extends the life of the system.