Mass applying to hundreds of positions with a single non-tailored resume has never worked and will never work. If you want interviews you need to get a referral.
That depends on the company. Some you need a referral to attach to your resume. Some you need to send your resume to the person referring you - who will then personally give it to the hiring manager. Some the hiring manager isn't allowed to know about the referral (the company like that I know of gives to the referring employee - but that is only about generating leads, not hiring decisions).
You have to figure out what is the way your target company works. Note that companies change how they work over time so make sure you have the latest information for the department you want to be in.
