It is January 7th not December 7th. It is national holiday in Russia and it is day off
It is possible to send a package from US to Russia. ~$50 for USPS ~$100 for UPS/Fedex. I did it several times and all packages have arrived (takes about 2-3 weeks)
Веселые каникулы! is translated as "cheerful recess", so it is not correct
Merry Christmas - "Хорошего Рождества!" or just "С Рождеством!" (usually used)
Happy Holidays - "Хороших праздников"
Happy Holiday - "С праздником"