I 130 approved..waiting for visa number.sponsor's status changes from PR to citizen

[divyabhasin]

I am 29 yrs old, unmarried and a citizen of India.My mother is a Permanent Resident of US.She filed petition I 130 for my Green card in January 2007under category 2B(Unmarried Sons and Daughters 21 years of age or older).My immigration petition was recently approved by USCIS and I am in queue for visa avalability.My mother is in the process of taking up her citizenship of US.Once she is a US citizen
1.will that change my category for visa from category 2B to category 1st under the family based Green cards?
2. will it help me in getting my GC faster?
3.Will my priority date remain the same i.e. January 2007 or will my mother have to file a new I 130 petition due to her change in status from PR to citizen.(which would mean getting a new priority date)?

status after citizinship will move atomatically from F2B to F1