Cool.  My first bit of advice is to get mom spayed when the kittens
are weaned...and don't let her back outside until she gets spayed.
They will actually go back into heat rather quickly.

Secondly, if you are using clumping litter for mom, replace it
with clay.  The dust in the clump litter isn't good for the babies.
As long as mom is taking care of them, all you need to do is
give them a little socializing.
Mom should also be on kitten food.  Contains extra calories
and nutrients that she will pass on to her babies.

I just did my first litter (also took in a pregnant stray)
this past spring.  Luckily mom did all the work since I
was totally lost but I did learn something.
At about 3 weeks the kittens started really exploring.  I made
sure the room they were in was kitten proof, nothing down that
they could get into.  At about 6 weeks I had to make sure there
wasn't anyway they could climb up stuff and pull things down on
themselves.  I was constantly bringing them new toys.  By 10 weeks
I was glad to turn them over to the rescue group to be homed.
Cute little guys but man do they have a lot of energy.  If you
aren't planning on keeping them you may want to look into getting
them spayed or neutered before you find them homes.  It can
be done as young as 10 weeks.

AG