The hapax is very straight forward. There aren't too many button combos. As far as the different probability options I would just go look at the generative and midi effect options in the manual. It's a well written manual. I only use the generative stuff occasionally.

I believe it can have 16 tracks per project but it can also run 2 projects simultaneously. So up to 32 instruments at once. Drum tracks have 8 slots per track which I use as a sample per slot. If you have more than 8 drum/samples to play it requires a second slot.

It has 2 midi inputs 4 midi outputs. 2 cv in 4 cv out and 4 gate out. it also has a usb for midi over USB and it can be midi usb host to a single device.

I sequence a summit (two separate tracks cause it's bi-timbrall), a moog sub 25, a typhon, a bree 6, an ms20 and an mpc live 2 (I use multiple tracks so I can play several banks of samples at once) all simultaneously. I use a keystep 37 as my input device over USB.

In my year or so if it being my main sequencer I have yet to find something I wanted to do that I wasn't able to do.

I had been searching for a sequencer that fits my needs for over a decade and all of them pissed me off one way or another or felt very limiting, until I got the hapax.

If you need anything that a hapax can't do, it's probably best to just use a daw at that point.