Assuming the point is in serviceable shape (it was replaced 10 years ago).... what is an appropriate setup to purchase from a big box store that will serve my needs?
I've tried to research this and have asked for help at in the plumbing department at said stores but can't seem to find any good advice on a simple on-demand setup that I can hook anything from 1 to 3 hoses to and run efficiently.

What is the rated gpm output of the sprinklers"

What is the diameter & length of the hose?

What is the GPM output of the well point?

The bottom line, if the well point cannot produce a volume equal to or greater than the combined output of the sprinklers it wouldn't matter if you used a firetruck for a pump.

That is the problem I kept running into at the stores. I find it hard to believe that such exactness is necessary.
Are you saying that it's not possible to have a pump/tank setup that allows one to operate a range of sprinklers and hoses from one hose, one small sprinkler, to three hoses and three large sprinklers?

Before we hooked up to city water thirty years ago, the house was supplied by the pump/tank in the basement. It supplied anything, pretty reliably, from one tiny sprinkler, to filling a coffee urn, to a full bathroom shower. No precise calculation there.

"What is the rated gpm output of the sprinklers"

They will vary, of course. One day I may be running one. Next day I may want to run three. The sprinklers may be of the type, in all their variable gpms, from any store on earth, used items from garage sales, and ones on hand. When they break, wear out, etc, they are highly unlikely to be replaced by exactly the same.

What is the diameter & length of the hose?

The hose/hoses length, diameter, and number attached to spigots will vary, of course, depending on my needs and what day it is.

What is the GPM output of the well point?

I'm assuming adequate volume to supply what I'm describing.
Anything from one hose with a small gpm sprinkler, to three hoses with high gpm sprinklers. If, after installation the point proves inadequate for the task, I put in a new point or go deeper.

Obviously you are assuming that all we need to do is drill a hole till we hit water and we will then have a well that will produce an unlimited amount of water...if it were only that easy.

You state that your well point could easily supply the showers and even fill your coffee urn, so let us examine those loads. Showers are limited to 2.5gpm, but even assuming you had the old showers that put out 3gpm, that is still a mere 30gal for a ten minute shower and your coffee urn probably used 1 to 1-1/2 gal.

Now let us examine the national averages:

National average daily residential water consumption per person =65gal.

The national average daily water consumption per household is 350gal.

The minimum acceptable water output from a home well is 3gpm and the well must be able to produce 300gal within a 4 hour pumping period.

Once the well is put in and they hit a sufficient supply of water to meet the minimum, they then determine the anticipated load for the structure and install an appropriate pump & holding tank. (for a minimal producing well they may require a 150 or 200gal holding tank).

As you can see, when you get in the shower there is already enough water in the holding tank to complete your shower and at 3gpm the pump should be able to keep pace with the shower, providing the well can keep pace.

Now let us examine your lawn sprinklers. Out of curiosity I looked up the specs on 15 different types of hose connected lawn sprinklers and found that they vary from 1.97gpm to 7.5gpm with the average at 3gpm so if you are running 3 sprinklers at the same time you have a combined load from 5.91gmp to 22.5gpm, but here again, even if we use the average you combined load would be 9gpm or maybe 3 times the output of your well.

The problems is, in your mind its only a lawn sprinkler, how much water could that need? Well, let us examine rainfall & lawn irrigation.

One acre is 43,560 square feet

With 144sq.in per sq.ft that would then be 6,272,640 sq.in.

If we then apply 1/10 of an inch of precipitation, whether its rain or irrigation that would equal 627,264cubic inches of water.

One gallon of water equals 231cu.in so 1/10" of an inch of precipitation equals 627,264cu.in per acre / 231cu.in per gallon equals 2,715gallons.

Or to express it in another way...Applying 1/10 of an inch of irrigation on one acre requires more water than what the average household consumes in 9 days.

Is there any wonder why many municipalities periodically have "Watering Bans"?