plankton, brine and rotifers

I know what photoplankton and zooplankton are, and also brine shrimp, but
what exactly is rotifers ?

I imagine for some this is a stupid question, but for me and a friend that
are only new to the salt water tank stuff it's all new to us.

I want to start off a photoplankton culture but no shops here seem to sell a
starter kit or anything for it.
As for Brine shrimp, it seems hard to find a packet of eggs that arn't
damaged from the gamma radiation things they go through at customs. They
only started this extra radiation a few months back I was told.

I have seen on the Flame Angel site the setup there, it's quite simple and
looks tidy, I would like to do similar, but I can't seem to find a source
for photoplankton.

So, is there anyone in Australia seeing such stuff ?