Some more information than that would be good. Like are you comfortable doing some hand coding? If so, I'd strongly recommend
Coda. There's also of course
DreamWeaver. If you want something easier to maintain then try
RapidWeaver but since you have existing pages I'm not sure how well it would work.
They all have FTP support in them. If you want an FTP client, check out
Transmit or
CyberDuck.