1/2 Barrel - gravel and plants question

Hi all, just started up a 1/2 barrel liner pond /w fountain pump after
reading the posts here, but have a few questions..

I did not put gravel at the bottom. Can you tell me what kind of
gravel is ideal? It is in a sunny location, I picked up 25 lbs of
aquarium gravel (epoxy coated or something like that), but I thought
was expensive. Can I get the small river pebbles from Lowes
landscaping section? It is alot cheaper more natural looking.

I got 3 plants: Anacharis, variegated Acorous, and sword plant, the
latter 2 have a small basket, Do I need soil or are they supposed to be
held in place by gravel? the Anacharis have a metal ring on it. I
read the acrorous needs shallow planting and my liner is 16" deep.
What is a good way to install the plants higher?

I saw some bareroot water lily in bags and instrutions calls for
gardening soil, I was wondering, You can put these with garden soil in
a basket and put in the pond? Wouldn't it make a mess? Do I get the
"aquatic soil" from the same section of the store?

What kind of floating plants do you recommend beside dwarf water lily?
I have been to the gardening centers and have trouble finding floating
plants.

I am using tap water right now, bought a bottle of declorinator, but I
read the chlorine will disperes in a few days. Do I need to use this
or not?

Finally, when can I add a couple of gold fish?

Thanks in advance