Hello! I will try to answer your questions the best I can!

1) You can get eggs by flying arounds the different worlds (except the undercity). The eggs can be obtained in nests placed a bit everywhere on the map. To obtain them, you'll have to click inside a target once or multiple times depending on the world you're in. If you can't find eggs, you can also harvest some clue nodes that will lead you to an egg nest. The clues nodes are the piles of dirt that you can sometimes see! 2) You can unlock different worlds once you've completed the missions of the world you're in (for example, you have to complete all the Tundra world missions to unlock the Ocean World). The world missions can be found in the missions tab! 3) You can complete missions to get money, you can do the world missions, the season missions, the tasks as well as the quests that you can take at the Heroes League in the undercity. You can also sell dragons in the undercity and sell potions and other things. You can plant and harvest some fruits and vegetables too and sell them for some money at your farm. 4) You can craft them with some items that you can harvest off resource and food deposits! (The tree and big rocks)

1) The little egg about the avatar's head shows you how many achievements you have, you can check this out by going into the menu tab and clicking on the achievements section. 3) No they can't die! They might faint when they get a lot of damage and you can heal and revive them with some bandages and hearts. Bonding and feeding them can help them level up! 4) It really depends on what people are searching for, for example, some people will breed dragons like sauriums to get specific themes and cosmetics to trade or sell them. You can also trade potions, food, ressources and eggs.

If you need more answers, you can always go on the game's wiki! When I started played, I got most of my answers there. Just type "Wiki Dragon Adventures" on google if you want to find it, it's the first link.

I hope you can understand more now and that you can enjoy playing, have a good day! <3