You can block seeing the applications. When you go (hang on, let me log in to see) to the Requests section, you can see all the things people have sent you. For a Group invitation, I see Confirm and Ignore in boxes. For a "causes video invitation", which is an application, I see Watch and Ignore in boxes, then below that in small font: "Block this application | Ignore all invitations from this friend".
So just block each application as you get it and you won't see them going forward. I never pay attention to the applications that come into my email box, or are on my page...I just wait until there are a ton over in that Requests box to the right, and do it en masse.
As for negative updates...maybe their lives are so good that the negative stuff is what jolts them to post. Maybe they don't feel it's as negative as you do.
What bugs me is the goopy "oh I love my husband soooo much". One friend posted that their DD was off somewhere, her husband took the day off, and they were going to spend the day in bed! UGH! Just b/c I went to school with you from 2nd grade on doesn't mean I want to know that, woman. And I don't know why she thought that *everyone else* on her friends list would want to know it, either...she has siblings, hubby's siblings, etc on her list...
I post what comes to mind, that I think won't bore people. Or if I want to whine and get a couple cyber hugs (b/c I wouldn't do that here) from my old friends if I'm sick. etc. Most of what I think to post doesn't get posted, b/c I don't want to bore people to tears, LOL.