#1
Im curious what the pros and cons may be of adding a new humbucker to my V.

Currently it only has one (Dimarzio Dp-100) in the bridge position, but ive thought what if i added another pickup of a sort to the neck position. Will it make a difference in the over all sound as a result of cutting into the body? or will it not make a difference?
#2
It will make a difference as a result of having a neck pickup - assuming you use the neck pipckup.

Some would argue that even the presence of the magnets of that extra pickup will affect the the sound picked up by the bridge pickup. And others will also say that losing those few grammes of wood will also make a difference.

Me, I'm of the opinion that if you habitually play through a cranked recto you'll probably notice nothing much that you do to your guitar. If you're all about the cleans then if you strain your ears then you might just tell the difference.

Ultimately you won't really know until you try, and only you may know the difference.