Yes, personal preference. As I said earlier, many members up the volume on the sub (to feel the boom) and/or the center (to hear the dialog) and sometimes the surrounds as well.
It may have set the sub's volume to -10 because the volume knob on the sub itself was a set little too high.
YPAO may have set the individual speaker volums a bit higher on the 465 then it did on the 673. I wouldn't worry too much about it.
You should also set the Center speaker to Small.
YPAO should be able to set the internal eq fairly acurrately
If you connect the subwoofer to the receiver with a...