Purchase Price and Black Water

I've really enjoyed this site and have just about decided to get a 2720SL. The couple of questions that I have are:

Realistically, what should I expect to pay for a new trailor vs MSRP?

I'm a little bit confused about the black water situation. How does one empty the black water hold? Is there a dump similar to other trailers, or do you have to remove it from inside?

If you get the microwave replacement for the oven, is it a combination unit or do you lose the normal oven functionality?

How does everyone feel about the three drawer cabinet in this unit, and do I have to give up something to use it?

I'm planning to go down and look at some units this weekend, but the dealership is a ways away and I'm trying to minimize my trips. I hope to have a lot of my decision made via my research and simply validate my plan when I get there. Maybe I'll even be a proud owner when I leave.

Thanks for any help you can offer!