Regaurding admission at dce?

my aieee rank is 18k n i m outside delhi candidate,i want to know in which round of counseling can i be called??also i want to know that suppose in my call letter i have been given a branch,now at tym of reporting at dtu if in case branch of my higher preference shows vacancy,so will i be admittted in that higher pref. branch or branc in which i m given allotment letter n den later i may b upgraded to that higher branch?