Do 301 redirects as Matt Cutts suggested becaue it is widely supported. Rel=canonical when you do not have the ability or option to do a 301 redirect.
Recommeneded: When moving from one site to another site. 301 redirect to a relevant page (from the old page to the new page), not to the root of the domain. No limit to 301 redirects per page. But there might be a limit to the number of levels (of 301 redirects) Google might follow.
This is a very good explanation by Matt Cutts regarding banner ads on your site.