A G0 move is a rapid move to reposition the tool bit (or table) for the next cutting sequence. On many controllers, it is not a coordinated move. In other words the X and Y may not arrive at the commanded positions at the same time. Normally the Z axis would be retracted to a safe location before executing the X/Y G0 move at the set rapid speed.
A G1 move is a coordinated linear move of one or more axis, and is normally done at cutting speeds. A G1 move could be accomplished at any speed you set in the G-code, up to the maximum speed the machine is capable of.
No, setting different step resolution would not apply to servos.