1. at; in
indicates location of action
彼女も今は屋敷で生活している。She is also living in the mansion now.
2. at; when
indicates time of action
3. by; with
indicates means of action
コーヒーでよかった？Is coffee okay?
4. so; therefore; (and) then; accordingly
で、何が言いたいの？So, what are you trying to say?
5. by the way; incidentally; now then; well
で、本題なんだけど、明日空いてる？Now then, getting to the point: are you free tomorrow?
6. and; then
indicates continuing action; alternative form of 〜て used for some verb types