Drew,

Most of the sample tracks on SoundCloud are 30 second in length. Is the platform capable of creating longer 2-4 minute songs right now?

Yeah -- we currently allow anyone to make music of up to 5 minutes in length. Would love for you to hop on Amper and give it a shot!

Is the mixing automated too? At what points are humans touching these compositions? (Meaning your soundcloud entries)

Thanks for asking. The entire composition, performance, and production is done by Amper. The music on Soundcloud is Amper's direct output without any human intervention.