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If I understand your question correctly, the more expensive lights have two
or four place settings so you can have one stop, two stops or less light.  I
wouldn't know about changing the color of the light although with a dimmer
it might.  Good quesiton.  She might try the more expensive lights with the
different settings for now though.  Ric in Wisconsin.

Distance is the great equalizer.  If you want less light, move the
light farther away.  In general, if you move the light twice as far
away, you get 1/4th the amount of light.

If you dimmed them, yes the color would change.  However, people don't
typically use incandesent lights.  Try compact florensent.  They are
much cooler.

    I can't be able to picture what you are trying to draw at your end, but
several "lamps" (?) laying on floor tangled with wires.  So, instead of
trying to untangle your daughter's lamps and wires, I would give a general
information.

- Depending on the shooting style you may need from 1 to 4 strobes.  And I
 think most people start, or usually end up with 2 strobes.

    - Most if not all strobes have built-in flash-trigger, so you only need to
     fire one and the rest will fire.  You can either using wireless or wire
    to 1 strobe

- You will or would need a Light Meter to measure the light from individual
or all strobe, so you can either setup the camera or adjust the strobe to
meet what you need.  "Light Meter" is one of the most important parts of
studio setup, or photograph using strobe

- Then you (or your daughter) will need learn some basic skill like how to
use all the toys, different angle, the distance between subject vs backdrop
vs strobe etc..

- Strobe - comparing to top-notch flash strobe is pretty inexpensive

- Light Meter - you may want to check with eBay which you may get a pretty
good Light meter for between $100-200 (or less).

- Wireless radio transmitter - you can get a cheap one for around $20-50

Most lamps will change in color temp as you dim them, I would guess  There
are some out there designed for digital photography.  However color temp can
be adjusted in post, especially if she is shooting in Camera RAW.

I would get away from the constant light source and move towards strobes.
Alien Bee has some good deals.  Nobody likes a 500W lamp shoved in their
face for very long...

If it is about learning, try the dimmers.  Could be fun and you both might
learn something.  Shoot white paper at different dimmer settings and see
what happens to the color temp...

In the end, if she is serious, she will one day own strobes.

Generally speaking, incandescent bulbs will change color temperature to a
more red color as the voltage is lowered.

As for not having dimmers installed, an on/off switch is cheaper to build
than a dimmer switch. And you are right, it wouldn't take much to put
together an extension cord with a dimmer switch- a trip to Home Depot for a
cord, electical box, dimmer switch, 4 wire nuts, and cover plate- maybe
$20-30 total and a few minutes work. (How-to: cut the extension cord where
you want the dimmer switch. Stick the cut ends into the box. Strip the
wires. Connect together with the wire nuts the white wire to the white wire,
and green wire to the green wire, and the black wires to the dimmer switch.
Stuff everything into the box and put on the cover plate. Caveat: this may
not meet electrical codes, and if done wrong, could cause fire or shock. But
I wear rubber sole shoes, and live next door to a fire station.)

She should also consider that light falls off with distance. If she moves a
light form 8' away to 11' away, it is down one f/stop. If she then moves it
16' away. it is down another f/stop.

Thanks to all who responded.  This info helps a lot.  And thanks to
digital photography, it's easy to shoot & observe, shoot & observe.