OGG
Master of the Meh
If you were going to use this in a performance situation, like for funk or new wave bass lines for example, what would you plug it into? A keyboard amp? A bass amp? A Marshall stack? Just go straight to the board? How did they monitor the Mini Moogs and such back in the day?
Straight into the PA is the norm for live use. Some folks use keyboard amps for personal monitoring or for venues that don't have a decent rig. I generally only use 1 or 2 synths live these days, but when I was using a whole bunch of them, I brought along a small mixer that compiled them before running that mix to FOH.
As for your second post/question, that's a tougher one to answer. Not my typical sound set, but when I do use those types of sounds they usually come from software. I'm an even shitier keyboard player than I am a guitarist, so things like weighted keys, velocity, and aftertouch are pretty lost on me. I don't need those dynamics for a live setting but have several keyboards that are equipped and capable for studio use. A weighted Controller with all of that stuff will set you back huge and you'd still need a sound source. Best option is probably one of the absurdly plentiful mid-range performance synths from Roland, Yamaha, KORG etc. Any fairly modern such products should be more than adequate.