5gal Hex-bio wheel-Betta & Cat or 2 small fish & Cat?

Hello,

I've been reading through some of the postings at this group and at
afew aquarium sites and just joined, any advice even though my new tank
is small would be appreciated. Perhaps later on I'll get a larger
tank...

After having had an aquarium many years ago when we were kids, I bought
a small 5 gallon Aquatech Hex with the bio wheel and the blue/white
carbon filter. I also got the 5-15gal heater since it is adjustable
and since we don't have central air/heating, it can get pretty cool in
our house during winter. I also have a small thermometer attached
inside and will get the small strip thermometer for the outside.
I set up the tank Sunday evening, with a little less than the 5# bag of
gravel, a few smooth stones, a plaster driftwood ornament (where fish
can hide or swim through underneath), 1 small round coral
ornament-about 2 3/4" in diameter, and bought two lilly bulbs in a
pack, will see how these grow, supposedly in about 20 days. I did
initially put 2 5# bags of gravel but read about how much harder it
will be to maintain and clean too much gravel-so took out a little more
than half, the bottom is covered well.
After reading on the web in this group and at other sites about the 1"
(full grown)/ gallon rule, I see how limited my options are. I didn't
want to start out with a large tank but perhaps I should have bit the
bullet and at least got a 20 or 29 gallon tank.
I'm leaning toward a male betta and maybe one of the small albino
catfish later on to help keep the tank kind of clean. I'll get the
vacuum gravel cleaner, will get the test strips that also check for
ammonia before I put any fish in. I've had a couple of male bettas
before, they are sweet-had them in bowls (medium sized, about half a
gallon), realize they do need better living conditions-I know the cool
house in the winter did them in, and they need more than betta flake
food-brine shrimp, blood worms for their diet.
If I get the small catfish, did I read right in that they eat algae
tablets and brine shrimp for their diet? Do they have to have the
algae tabs every day since don't they eat the stuff at the bottom of
the tank?
One more question-when I removed the excess gravel from the tank, I
noticed a small amount of fine dust from the gravel on some of the
larger stones, the driftwood ornament and coral, and a little on the
outer lower tube of the pumps intake, Would the gravel vacuum remove
this or will I have to take everything out again and re-rinse
everything?
I realize this is a small tank, not the larger tanks that most people
have but any advice would be appreciated, small tank owners chime in
also, please- thanks and
regards,

ko57