When a call comes in, the phone displays the name from the Address Book and the number. Is there anyway to make it display the slot the number is saved in, e.g., Home, Work, Other, etc.?

It should show that by default... something like the attached picture...

It should be default. i.e. work shown as (W), home as (H), mobile as (M) (in the call list I might add)

If there is only one number in the contact, it might not show which field (i cant remember anymore)

Guess it's just my luck that the default doesn't seem to work for me. I have not changed any settings regarding this, as far as I know. But, I don't get the location info with the call.

As far as I know, it is not theme dependent... but you could verify by trying a different theme. I know the "call" screen can be different from one theme to another... but at this point, I am not sure... YMMV.