Yeah, I'm also against new members not being able to post links - I've often needed to do that as first-post when joining a new forum, for the same reasons tomos
states. It would definitely help bring down spam, but... just how much spam do we get, and how much would it annoy legitimate users?
Limiting the edit capability to, say, X hours with under 10 posts would probably work out pretty well. Wouldn't be much trouble for regular users, and spammers are very unlikely to do more than a few posts at most.
As for edits showing up on "unread threads", I don't think it would be much of a problem, unless every
edit would show up as an entry. Imho it'd be enough for a thread to be flagged as updated (only showing up in the list once), but probably with a per-thread "list of changes"?
This has to be done right - we don't want to flood the board with update thingies, and any new "tools" have to be easy to use