I rewrote a notice because I thought it was too simple and did not include necessary information to make readers know about the news. But I am not sure whether the changes in red are proper or not, and whether the changes are natural and acceptable to native speakers. Could you help me check?

Volunteers Needed

January 9, 2012

Because there will be an international conference on globalization to be held inBeijingon May 16, 2012, volunteers are being recruited by the Postgraduates’ Association. Any graduate student interested in participating the activity could come to our office on the fifth floor of the College Office Building before March. 1, 2012.

Postgraduate Association

Volunteers Needed

January 9, 2012

There will be an international conference on globalization to be scheduled for May 16, 2012 at Yifu Conference Center of Beijing University. Volunteers are being recruited to greet and attend to guests from 8:00 to 17:00 that day with 1 hour break at noon by the Postgraduates’ Assocation. Any postgraduate student interested in participating in the activity could come to our office to put down your name on the fifth floor of the College Office Building before March. 1, 2012.

Postgraduate Association
Volunteers Needed January 9, 2012

An international conference on globalization will be held on May 16, 2012 at the Yifu Conference Center, Beijing University. Volunteers are being recruited by the Postgraduates’ Association to greet and attend guests from 8:00 to 17:00, with a one-hour break at noon. Any postgraduate student interested in participating should apply at our office on the fifth floor of the College Office Building before March 1, 2012.

Postgraduate Association
Thank you very much!
Teachers: We supply a list of EFL job vacancies
Thank you for your check.

P.S. Which version do you prefer, the first one or the second one?
I revised only the 2nd one. Use that.
Thank you!
Students: We have free audio pronunciation exercises.