First of all, you don't need to be able to play keyboards, guitars, or other traditional instruments great. There are plenty of musicians out there who can't play instruments very well, and have no clue about music theory, yet created beautiful music, just by using their ears and having very basic instrument skills. 

If you are getting into electronic music and live performance, then I would not invest my time into traditional instruments. Most electronic music is not performed by playing all the individual parts of the songs, because that would require a 10 person band, and it sounds like you're going to perform alone. 

Ableton Live is a good start, I would get into that software more, and then look for input devices to use with that software. If you are looking for a low level device to start and stop sounds or adjust volume levels, you can get something like the ACP40 by Akai. If you are looking to do more advanced stuff, and add visual elements to your show, and also like to develop your own software and work with automatically generated music, arpeggiators and sequencers, then something like AudioCubes by <a href="http://www.percussa.com/">Percussa</a> will be a great investment. This tool even comes with free software so you might not need to buy much more than that to get started. 

The Overtone suggestion here is a very good one, since you are a developer. Also look into Supercollider and Max/MSP, two well known tools for computer music.