I have had ponds in various forms, most recently in an old wash tub about the size of a half whiskey barrel. It didnt need a liner, and that's the only flaw i can see in your plan. One pond liner i had was a very stiff plastic, would have been hard to fold into a small enough sizeto fit in a whiskey barrel. Plus those folds build up gunk quickly. For something that small, you'll want it in the shade if you want to keep it from growing algae and keep the water temp okay for plants and fish.
Winter is an issue...i had a goldfish in it one summer, he got pretty big and i didnt have anything to bring him inside in...gave him to someone with an aquarium, and, um, he took some horrible funk to all her other fish and they all ended up dying. Oops.
I've played around with lotsa different bubblers and spitters and cascading down through pots or even up through an old coffee maker (its hard to explain!). I even had a mini japanese bamboo "clacker" - the water dumps into a section of bamboo and when it gets full enough, the section dumps into the pond with a loud CLACK. I loved that feature, but it took a lot of fiddling and adjustment on water pressure to get the right flow. I would use zip ties and partially close the hose between the pump and my feature to reduce water pressure, but there's no way to increase it - if your pump doesnt push enough to make your feature work, you end up buying a bigger pump. (i think i have 3 different ones around somewhere!) also, clear water hose builds up algae faster than black (duh

)
Anyway, have fun. I'll have another one next summer probably in the wash tub on our deck again...someday maybe a big in ground one again also.