Despite my privacy concerns with Google generally, yes I would say GMail is the best free email provider (until iCloud goes live in the fall).

Yes, GMail can be synced easily with Mail (not iMail) on all your Macs and smart-devices, since it uses IMAP.

You might consider simply forwarding your Hotmail account to GMail, which would make it easier to slowly transition over. Having said that, fair warning: come the fall I will be telling people that GMail is for suckers.