Questions about networking and referral

So if I have no idea what division am I interested right now, does connecting with bankers from different divisions help? For instance, if I ended up applying M&A jobs, will people in RX or even S&T that I networked and referred help? (Same question for location. If I connected with some people in NY office, will that help if I applied job openings in LA or TX offices for the same bank?)

Apart from alumni, does connecting with bankers from other schools help? 

Also I'm confused how's the overall referral process is like. I saw people said a butch of bankers from your school gathers to do resume screening but there're also other people that says your resume will be uploaded in an internal portal if the networking goes well and some banker wanted to refer you.