can't see where the resistor goes
Oh.. Hmmmm. The UNO schematic shows a 1 meg ohm resistor across the crystal:
Anyone have experience with this resistor + or - ??
"Stable" - batteries are often used.. 4x NiMH gives about 4.8V and many people find this OK. But when they are running down and motors are driven by same batteries, failures occur. So: Depends on what motors you might be using.
"Real Stable" would be a voltage regulator fed by 7.2 to 9 volts, putting out 5.0V . Like the voltage regulator circuit that is adding lots of components to that Arduino board...