Ok first of all, that size tank is too small for silver dollars they get BIG! second you might get away with 2 american flags, but then you couldnt have anything else.
from the list you have of fish you want, there is too many you will be over stocking the little tanks.
I queit like the tanks have seen them in animates, good tank for in the bedroom. Does it have a heater? I have not seent he setup with a heater?
Livebearers are a very good choice to start off with along with some Bristlenose which are a type of bottom dweller.
You are pretty on the mark with your "philosophy" although there are something down the track that are not queit as simple as that.
The silver coloured "neon" like fish you saw, form what you describe i would say they are rummy nose tetras, and are alot hardier than neons.
much better idea!
Clown loaches will out grow your tank very quickly, they get to about a foot long.
If you dont want a livebearer to take over your tank try mollies, they give birht to small amounts of fry, at a larger size than others, higher survival rate, but less fry, and if some do make it to teenage hood and are not eatin by other fish them you could sell them.
a good i dea is to heavily plant a little tank like that, it creates its own little eco-system for them and the plants also help balance the water conditions and act as a filter themselves. If you are going to stock you tank heavily a gravel clean along with a water change should be in order.
Buy a gravel vacum, makes things much quicker and easier.
The brislenose will keep the alage down, all snails do is become a nusance and will eat the plants.
Do not get some bigger fish like you said above, not smart for such a small tank.
Cheers Shae