No, you do not need to do that. All steps will be processed completely online.
If you did not receive your confirmation email after applying, then please check your SPAM folder and privacy settings in your email account
Yes, of course. Each person must have a different eVisa/ETA.
An eVisa/ETA can be acquired effectively anyplace with a web association and it spares your time and effort instead of applying at the missions, embassies or at the ports.
No, you do not. You only need to show your passport for checking at the airport.