1/2: College Scorecard lists CPP at $79,792 and UCSB at $73,907 for initial earnings for ME graduates who received federal financial aid. Probably within typical year-to-year variation. UCSB is more research oriented, which may matter if the student wants to go on to PhD study.
3: https://catalog.cpp.edu/mime/media/53/3477/College+Board+Advanced+Placement+(AP)+Examination+Credit_2020-21.pdf and UC Santa Barbara General Catalog - Advanced Placement Credit and Chart but then you have to check the ME and general education requirements to see which are actually useful.
4: UCSB is more of a residential university, whereas CPP is about half commuter, so UCSB is likely to have more campus-centered student life. It also has a “party” reputation (but residential universities tend to party more than commuter universities) and is right on the beach.
UCSB lists 148 quarter units (out of 180 quarter units to graduate) as required: https://me.ucsb.edu/undergraduate/admissions/bs-requirements . However, the sample program at Academics | Mechanical Engineering - UC Santa Barbara lists 191 quarter units.
CPP lists 127 semester units as required: Program: Mechanical Engineering, B.S.: 127 units - Cal Poly Pomona - Acalog ACMS™
Note that 1 semester unit = 1.5 quarter unit, so the typical 120 semester units to graduate = 180 quarter units. (But ME majors commonly require more than that.)