That's the MadBean EdgeLord, clone of the Ibanez SB7 Synthesizer Bass- a pretty rad OTA based envelope filter with a distortion circuit for the synth voices. The Envelope mode is a clean LPF, Synth I is that same LPF with a soft clipped distortion driving it, while Synth II is a bandpass filter with the distortion heading into the filter
Yes, I use stamps. I have a set of custom 16pt Peignot font, as seen on the Edgelord, and a few different sets of typewriter type fonts made by Contact USA called Pegz seen on the others in that post.
The ink I use the most is StazOn brand opaque white. It's a solvent base, and it's cheap, durable, and readily available. I do have some other inks, but because cleanup with them is such a chore, I don't use them too often