To take things out of order:
Filters don't suck up fish poo, that's the fishkeeper's job. Sand makes this much easier, you just hover the siphon tube about half an inch above the sand and make small swirling motions. This lifts the poo etc off the sand and the siphon sucks it up. You will also suck up a bit of sand. Just wash it in tap water, drain it as well as you can and put the sand back in the tank. The tiny bit of chlorine in the water stuck to the sand won't be enough to do any harm.
The snail on the glass behind the wood looks like one of those variously called pest, bladder, tadpole or pond snails. They arrive in the tank on live plants, either as tiny snails or eggs. They are not a bad thing to have, lots of people reckon they are a necessary part of an eco-system. They will get out of control if you over feed the fish as they'll eat the left over food and multiply.
I have both these snails and the tiny flat spiral kind in my tanks.
The bubbles on top of the water are normal in an Edge. Gasses that come out of the water can't escape and are trapped by the top glass. The way to get rid of them is very carefully put a small wedge under the back of the stand. Just enough to tilt the tank so the bubbles move to the square of air.
The bubbles on the wood are not very clear. Could they be trapped in the translucent white mould that is common on new wood?
You said in a previous post that you'd put guppies in the tank - but the fish in the photo are not guppies. What are they, some sort of tetra (as they have an adipose fin)? If they are tetras I need to warn you that only a very few tiny species of tetra are suitable for a 23 litre tank.
And just to check - are you testing for ammonia and nitrite on a daily basis? Since the tank is new and you have fish you are doing a fish-in cycle and need to keep both of those below 0.25 by doing as many water changes as necessary.