Well i don't think so that the campaigns will lower their rates because these rates are running from many months no matter what is the price of bitcoins . I would say that the rates of campaign per post are universal rates So we will not see any change .
Of course they will. Why would they bankrupt themselves? I don't think those guys have a few thousand coins put aside to supply sig campaigns for the next few years. It goes out as fast as it comes in. And they're gonna be taking in less bitcoins with a higher price.
Some of them will drop prizes and not only because Bitcoin price rises. It is also about supply and demand - it looks like now more people is interested to earn from signature campaigns, so automatically rates will goes down.