For the earthquake stuff, you can check out Carl Olof Jonsson's Sign of the Last Days. It takes each of those signs, one-by-one (famines, earthquakes, disease, war, etc), and shows how the JWs have exagerated and lied. It's a great book with lots of documentation and references. But, being that the author is an ex-JW, the information is mostly targeted right at JW literature. So, if you're not careful, you could tip them off. By the way, his other book, Gentile Times Reconsidered debunks the whole Babylonian 607 thing and 1914 and I recommend it as well, though that is a bit harder read. Last Days is a lot lighter and even enjoyable, seeing the overwhelming documentation against them. I'm sure they're available elsewhere, but freeminds.org has them. And, the earthquake chapter can be found online at: http://www.preteristarchive.com/dEmEnTiA/jonsson-herbst_dd_01.html
Another thing to look at is the US Geological Society's site. Check out http://earthquake.usgs.gov/ I clicked on the EQ Facts and Lists tab, then magnitude and intensity, then an article called "Are earthquakes really on the increase?" The direct link is http://neic.usgs.gov/neis/general/increase_in_earthquakes.html Can't find it now, but at one time I downloaded a list that contained earthquakes going back to the late 1800's. Whenever I debate them, I like to use neutral sites to avoid setting off the apostate radar. And if it's a neutral, non-religious site, they may actually look into it.
Another thing is that the WTS more-or-less admitted that earthquakes weren't on the rise. I think it was in an Awake from March of last year. From what I remember, they acknowledged that scientists say that there has been no increase in earthquakes. And while not coming right out and saying they agree, they do seem to have a BUT in there. BUT (as if to say "yup, that's true, BUT"), Jesus didn't say any one thing had to be on a grand scale (more war, more disease, more earthquakes). He just said that all those signs would be occuring. Which totally goes in the face of all of their claims over several decades. They've always said things have increased since 1914, not just that you'd have all of these things happening at once. So, as long as there's earthquakes someplace, starving someplace else, a war someplace else, and disease someplace else, the end is coming. When in history hasn't that been true?