from www.site.com to wwwsite.com/ you wont lose anything, it ios not a 301, it happens by itself.

but /page to /page/ you will lose a bit.

I always suggest non slash as people are much more likly to leave a slash off then add one on when creating a link.

Make sure that whatt ever you decide that you keep to in your internal linking, you have no control over what others do.

DNS, resolves a name to a ip number,

that ip number should route to your website. Inthe headers of the resquest is the domain name, your web site should be configured to accept either all requests on a ip number and port or filtered by host headers (domains names), add all teh host headers needed, then in htaccess 30 to the pirmary domain name.