Thank you guys for your answers.
As much as I would love to play around with the throttle right away, I agree, that the first thing would be to get a readout on sensors and display them. Then I could expand on the parameters I can manage. And once I have the parameters I need to change something else, we'll approach that.
Henry, I'd be happy to accept any help in programming so I can take a first look at what code actually looks like and see someting very basic that actually works before I try to expand on it.
Could you guys give me a shopping list of what to get?
Maybe we could start with the basic hardware for the Arduino (I don't even know which one or which kit to get)
a display (if android readouts are too difficult for the beginning)
and some sensors (temperature, hal sensors for speed and crank cadence, maybe a photo sensor to automatically switch on the backlight when it's too dark)