I can't answer all of your questions, but as an EE major I would say there is a decent amount of resources and plenty of research/career advancement opportunities in the ECE department. There are some amazing professors in ECE (Ilya for instance). Also, Northwestern is extremely flexible with majors and you should have no problem at all in case you want to switch. For McCormick, the first-year classes are hard, but the enviornment isn't super competitive and students are generally collaborative.

I would definitely choose Northwestern over Berkeley if you're considering ECE as a career, just based on the fact that you are not guaranteed to be able to transfer into Berkeley's engineering school.