Electronic music is just making music with instruments that require electricity. How you go about that is up to you.

Do some research on the history of electronic music a read up on all of it as it will put some perspective on things. While most folks probally don't do this, it is a good idea as working solely in MIDI, as it is the most common, might not be something you enjoy doing as much as say cutting tape. (humour) Still you will probally find out that digital audio and MIDI are the cheapest way to go. But it is a creative endevore so try not to get sucked into the hype surrounding the technology and try things that seem like they may appeal to you.

Most of the influences you have mentioned use an assortment of stuff to that is hard question to answer. But apparently you have a computer so after digging up the info on what was around in the past , you can start with the computer emulations that seem to be every where today. There are meany free and shareware programs that will get you into the basics of synthesis and sequenceing cheaper than the hardware brethren.

There is much that goes into this as it is a close relationship between the arts and science.

Most important is not to be afraid of any of it. Jump in head over foot and push every button or click it at least. See what it does, learn to solve the problems when something crashes and enjoy the unintended results. (Always leave some sort of recorder running) It will start to make more sence over time but if your scared to push a button then electronics and electronic music will do little for you.

Also when looking into new instruments don't shy away from some things like kits and what not for the likes of Paia and MOTM as they will also help you gain a better understanding of what the hell is going on.

As for playing music with electronic gear, go buy something and play it. When you get bored with it, buy something else.