*Want to have some flexibility to change my major to CE, EE, or Mech. E in the second year (almost impossible at UCSD & UCSB) since I am not too sure whether to pursue CS
UCSD would not be an option. UCSB could be an option to switch but not guaranteed. I would contact the Engineering department at UCSB and ask your chances to switch majors before eliminating UCSB. Since you are already admitted into the Engineering College, change of major would be an easier process.
I cannot comment on NEU.