Bear in mind that the people that have booked excursions through Carnival will get top priority when it comes to boarding the tenders. After that it goes by ticket number (which you have to pick up at a designated location earlier that day). If you do book through Carnival, make sure you get ahead of all the people with tickets that clog the stairs and hallways even though their number has yet to be called.
1--You get tickets the morning you get to a tender port. The time will be in the "Capers" you get the prior night
2--One of the lounges. Again, that will be announced in "Capers"
3--The first tickets are for about 30-45 minutes after arrival. The last are for about 2-3 hours after arrival
4--After the last ticket number is called, they will begin "open tendering". Basically, all you do is show up. You're on the next tender that has space for you. And, by then, that'll probably be the next tender at the ship.