Post Graduate Work Permit

I have to apply for a post graduate work permit from buffalo. I have completed my masters from toronto in one and half year. Do you have any idea for how long buffalo office give me post grad work permit. I heard if you apply to buffalo they usually give a 3 year PGW permit regardless of the length of the program.
And also i have to renew my TRV as it expires in about 3 months. Do they still provide same day service ?? If not do you know how long do they take? Is it better for me to get a US visa and apply from buffalo office in person. or if i dont get the US visa can i mail them my passport and apply my PGWP from buffalo as i have heard that you get a 3 year Post grad work permit even if your length of program is about a year or so ..

Any comments on this matter would be appreciated
Thanks.