Q1: Yes, it is common for schools to not invite international applicants to visit the campus for an interview (or a recruitment visit), because it is expensive to travel that far. Instead, they might phone or Skype with you. However, not every school has interviews, so not hearing about an interview could mean
i) you did not get pass the interview stage,
ii) they have not yet decided to interview you, or
iii) they do not need interview for admission.
Q2: Every school does things differently. Yes, some schools will notify applicants step by step, which has at least two meanings:
i) they send acceptances first, notify about waitlist second, and then rejection don't come until much later, and/or
ii) they decide on a small shortlist first, notify them, then make more offers in small batches until they get the number of students they want
Here is how I would interpret results: you are not rejected until you get a rejection notice (which could not be until April or maybe even the summer or maybe they never tell you). The exception is if you are certain that a school has sent out all its offers, then not hearing anything is likely a rejection.