I realise the schottky is best on the motor, it just makes resoldering a motor a bit tricky at times. Getting lots of good ones so you can have one or two for each motor soon gets expensive so I have mine on the motor wires, about 2cm from the motor itself. A bit of a trade off but it makes motor changes a lot easier.
I'm intrested in what you're thinking of for the buttons, trying to think a bit differently....
How about a car key style remote fob?
or maybe you've got simple membrane type buttons.