Question for Jehovah's Witnesses?

Just wondering, why do you not celebrate any holidays? I don't mean this in a criticizing or condescending way. I'm genuinely interested in what your reasons are for not doing so. I have heard that Christmas and Easter have pagan origins...is that why, and you believe it's wrong because of that? Is it true that you also don't celebrate birthdays? Also, since you do obviously believe in the birth and resurrection of Christ, do you have any kind of special Kingdom Hall meetings for these things around Christmas and Easter and just not do the whole Santa, Christmas trees, and Easter bunny stuff? Thanks for your help :)