I already addressed the search and stickied topics in the other topic, but I can sort of explain the link situation.
Basically, we've had a huge issue with spambots signing up in the wee hours of the morning and posting links in previous months. A lot of inappropriate stuff, a lot of general spam - bad stuff. Posts with links included are now put through a moderation queue until the user hits a certain post count.
It's not always convenient, but it has really helped with the situation.