Sony people will only deliver the TV, I doubt they can help since may not be expert in it, if spolit drill, you scold them?
How big the hole is up to you to decide, the best is your contractor to do the job as since to make a complete reno product to you, and by their experience, they know how big the hole to run the cable and maybe the hand size to fit in, in case you need to put your hand in to run some cables work like speaker cables.
Hope it helps.