I don't think you should look at it as "how much do you think a dealer would consider coming off the MSRP?" You should have a number you are willing to pay and a number you're not.
There's a "How Much Off MSRP" thread somewhere. It seems like you should at least get 2k off. 3k is possible. And some have had even more. When I get ready to buy this summer (assuming demand hasn't picked up dramatically) I'm aiming for at least 3k off MSRP.
And yes, settle on price, then talk lease when you have a firm number. There are a few dealers who want to try to sucker you into paying more for a lease.