Thank you for your answers guys! About the full usage of the four channels, I didn't feel comfortable about this because I was afraid to make some cacophonous music, so one pulse channel has basic rhythm, the other one has primitive melody, and I love the wave channel with distorted synth producing bass and advanced melody. It's a personal point of view. I will obviously try to use the potential of the 4 channels and to turn down my basses, I love experimenting and having multiple recipes to cook in different ways.
Really, huge thanks to you, you are the first people actually orienting me somewhere.