Celebrations and Customs

Q: What is the ruling regarding birthdays? Our muslims greet one another on this day and feel insulted if one does not greet them. Another issue is regarding birthday cakes, gifts and parties. Please advise.

Q: What is the ruling with regards to Easter celebrations, Easter eggs, hot cross buns, etc.?

Q: Is it permissible to tell someone "happy birthday"? I know its not a day to celebrate, nor do we do so but people feel appreciated / acknowledged that at least he remembered my birthday. Sometimes, some people take offense if you "forget" to tell them?