Newbie!

Hi I decided to get a tank the other day....

so I bought a 30 litre hexagonal tank, a heater and Elite Stingray 10
Underwater Filter (for tanks up to 50 litre) - the filter seems really
big!

I bought white gravel one or two plastic plants and a small statue
kinda thing. Looks a bit plain and you can see the filter just sitting
there at the back of the tank.

Cleaned everything including gravel and then filled with water.... put
in some anti-chlorine stuff, switched the filter and heater on and left
for 24 hours... but the water still seems cloudy!?!?

I want to get fish this weekend, but have been told to get some real
hard fish that can survive anything.... any recommendations!?!?

I want it to look nice but think it looks plain, but as its only small
I dont want to overpower it.... Can I add and remove stuff from the
tank after the fish have gone in??

Also, I didnt get a light.... but have seen the moonlight ones on
ebay.... tubes and leds... which are better....

Any recommendations on styling or general advice about cloudy water and
general stuff would be much much appreciated.

Thanks

Peter