BTW, the existing valves look like they are soldered onto copper pipes that
protrude horizontally out of the wall. There is round aluminum circular
disk around each pipe where it meets the wall and roughly 3/4" of exposed
copper pipe sticking out beyond the circular disk before the beginning of
the solder connection.

The existing two pipes are around 9" horizontally apart from with one of
them mounted around 3/4" higher than the other.

Is it problematic the way the pipes are 9" apart and protruding out of the
wall (with one of them about 3/4" higher than the other), or will the
plumber simply be able to cut off the old valves and fit some angular
attachments to get a single handle valve installed without having to cut
into any drywall?

Thanks,

J.