Will i be notified if I do not get invited to candidate weekend?
Not really. But you can consider it being not invited if you don’t get the invite a week before CW - AD knows that there will be visa issues, so will send them all out beforehand.
Are the invites sent out by email or post?
Sent by email notification with a link to candidates weekend portal to register to attend. Parents also receive an email letting them know their child was invited. Some schools email servers reject communication from college admissions so make sure to check your junk mail/spam folder in case it is there. My son’s was buried and he would not have ever known had NYUAD not sent parental notification.