NWR: Switching Jobs

I am REALLY close to getting a new job....yesterday a place I interviewed at called me and said 'we really like you and want to make you an offer but cannot get in touch with your third reference....' (I solved that problem but point is, that sounds very promising to me.)

When I interviewed, they wouldn't let me get around the salary question (I'm concerned that I'll negioate against myself) so I gave them a range. Now, if they offer me the top of my range, can I still ask for more money?

And, how do I tell my boss that I'm leaving? She's been really great to me and I don't want to leave on bad terms.

TIA for your help!