Celebrations and Customs

Q:

1. Is it permissible to send seasonal greeting cards to non-Muslims at the time of Christmas so long as there are no religious symbols on them and without the intention of celebrating or supporting Christmas?
2. Can the following from al-ashbaah be used as a justification for sending seasonal greeting cards at Christmas time?

In al-ashbaah it states that if a person says regarding a non Muslim: "May Allah let his kingdom last for a long time" and his intention is that he may be given hidayat in future, or that the Muslims could benefit through his contributions of jizyah etc, then this is permitted. 

Q:

1. Is it permissible to say have a happy new year when Islamic new year starts (month of  Muharram starts)?
2. Is it permissible to say have a happy new year when the Gregorian calendar new year starts (month of January starts)?
3. If its not permissible to say have a happy new year then what is the reason?
4. What did Prophet Peace be upon him and the Sahabah do or say to each other when the new year commenced?

Q: I had a question what's the ruling on Muslims celebrating non Muslims holiday?

Q: Is it permissible to write the following line in a letter which will be sent to employees of a company before holidays: ".. and may we also convey our best wishes to John & Henry and other colleagues who are celebrating Christmas"? I.e. without wishing them Merry Christmas but just "convey our best wishes"

Q:  What is the ruling on uttering "Happy holidays" to disbelievers (i.e. Christians)?

Q:

1. What date was Prophet Isa(Jesus) peace be upon him born?
2. What date was Prophet Isa(Jesus) peace be upon him born raised in the sky?
3. Was Isa (Jesus) peace be upon him born on 25th December?
4. What detailed advice should we give our children regarding Christmas?

Q: My family are not Christian, they belong to a kuffaar sect who act like Muslims (alevi), however this year they have decided to have a family Christmas celebration on 25/12. They will exchange presents in a kris kringle (secret santa gift exchange where everyone anonymously buys one person a gift) and will share a family meal with traditional Christmas foods.

1. Can I attend this gathering?
2. I'm pretty sure I can't partake in the gift exchange, is this correct?
3. Please advise on Surahs/duas for me to say to help my family become Muslim.

Q: I had a question about thanks giveing? Is it ok for a Muslim to celebrate it?

Q: Is it okay to eat cakes on ones birthday? We do not take pictures or play music on birthdays. We go out to eat and cut cakes when we come home. Is this okay?

Q: On the occasion of Diwali, can we wish hindus happy Diwali? Also, can we take part in the fireworks celebrations?