The first is easily my biggest annoyance on the forum. A member, usually but not always a new one, will go down the list on general discussion and add a useless post to around ten threads. This bumps dead threads to the top and pushes active ones to the bottom and frequently kills them. Theres really no good way to prevent this one though.
The next one has been a minor issue for along time now but as of the last few weeks its gotten way worse. Members have been bumping really old threads with no useful content, most of the time its hardly relevant. Presentation is easy for this one, lock threads that are over 2 months old and add a note that if they truly feel it should be unlocked report it. This will get rid of useless posting while still allowing the very occasional useful bump to an old thread to be done.
I'd also suggest a rule change. For brand new members they should be banned unless they have actually contributed something on top of that behavior. If that's what they do they're more trouble than they're worth. They generally are just link spammers anyways. There should be a rule in place so that if non-newbies to this an infraction can be issued (if one is not already) for that type of behavior.
While a lot of these posts get deleted when noticed, flagged as fluff posting, I am suspecting most of these members come from few particular countries. We are developing a solution presently that will hopefully eliminate those kind of posters altogether. Can't delve into details yet, but its a custom solution.