I'n using Raspberry Pi 3. Never tried the setup with Raspberry Pi 2 which I also have, and I use it as hybrid MIDI Thru / MIDI USH hub device. Seq24 is capable of doing quantization while recording MIDI notes/events. To be honest, I use Alesis MMT-8 for quick MIDI jams. I draw notes via mouse on seq24. But yes, you can use external MIDI keyboard to record MIDI sequences on seq24. I tried that many moons ago, and it works.
RE: JAM: Epilogue