nexxos
1
I'm powering my stepper motor and motor driver with a 12V 5A power supply and was planing to also power the Arduino with it.
Simple question: would the 5A fry the Arduino or won't it matter at all?
I researched some time and couldn't find a current limit, but well, better safe than sorry and asking you guys 
Its not so much the current you need to worry about as the board will only draw what it needs.
There is a caveat in that many official boards have been seen to pop the voltage regulators at the 12 volt mark but the clones seem more tolerant.
Run all mine at 7 to 10 volts to make sure I keep them happy.