Apply under F4 or F2A visa?

[grncrd]

Hello,

I hope you can help me.

My brother (a US citizen) was sponsoring me on:

Preference Category: F4 - BROTHERS AND SISTERS OF U.S. CITIZENS
Your Priority Date: 14FEB2012

Now my parents have their green card. (Not citizens)

1) Can my parents sponsor me instead? Will it be faster?
2) How much longer would I need to wait on the F4 category?
3) Can a person transfer categories, or do they just re-apply?

PLEASE HELP!!!!

Thanks!