Welcome to the forums, IMangel.
I don't see how either of those plug-ins would create a Panda problem. StickPost just gives your home page some static content, right? That might even help. And as long as you don't mash-up the post order too often, PostMash shouldn't create any Panda issues either - at least as far as we've identified them for now.
I also can't see how sharing on Facebook Walls would work against you. And if you ever want to turn comments back on, there are plug-ins like Akismet as well as challenges to stop automated spam that can cut down comment spam dramatically.
Are you concerned because you have already seen a traffic drop that corresponds to the two Panda roll-out dates? Or are you trying to pro-actively prevent trouble before it shows up?