so why did Littlefinger have Arryn poisoned by Lysa?
what would it have mattered to him if Arryn found out the kids were Jamies?
as for framing Tyrion of trying to kill Bran back in season 1:
Why didn't Tyrion say to Catelyn "what jewel encrusted dagger?" or "I never lost a dagger to Littlefinger in a card game"
heck, does Tyrion even know about the dagger that caused this whole mess?
Yes, he did. I'd have to watch a lot of episodes again to find the exact place and quote, I think it's the scene after Catelyn takes him captive just before they are ambushed on the way to the Eyre, Tyrion is talking with someone that if he were to assassinate someone it would make no sense to give him an item that can pin the blame on him.