"What is the difference between an 'under counter' kitchen sink and a 'self rimming' sink?"
An "under counter" sink is just that - it mounts from the bottom of the counter. A self-rimming sink has overall dimensions larger than the opening in the counter and sits on top of the countertop. It requires no additional rim around the outside of the sink, and generally will give you a lot less problems down the road. Why? Because it cannot fall down and gravity over time will not open the seal between the counter and the sink with a self rimming sink. Under counter mounts can be used with solid surface or granite, marble counter tops. If you're using Formica type counters use the self-rimming. For tile we like to recommend selfrimming. Under counter sinks, over time can have problems where the sink and counter meet.

"I'd like to have 2 extra holes for an air gap and hot water dispenser and was wondering if you can drill extra holes in my sink for me?"
Yes, we can do that. Just enter the number of additional (EXTRA) holes that you would like here = $50.00 . Please note that we do not take back sinks where we have drilled holes and also that we do not guarantee that we will drill the hole in the sink in any particular place. We will drill it where we feel best and cannot promise to drill it in any exact/specific place on the sink. With Revere brand, please allow up to 4 additional weeks if you order additional holes in your sink. Once you place the order for a modified sink it is your sink (we will charge your credit card and the order is non cancelable).