My clash royale troops and other supercell games are very blurr

Everything goes through game.clashroyaleapp.com

There is no end-game. You play to get higher trophies and go in better Tiers.

People wait at first because you don't start with 10 Elixir but only 5 so they wait to accumulate the full amount and perform a better attack (use more than one unit at the same time) there are million strategies when to play what card.

You have the basic idea, you defend your towers (the more towers you have, the better you'll do) so they don't attack your King, whilst you attack them to take their towers down. Check some "How-to"s on youtube for tips on how to start playing if the tutorial wasn't enough for you. And you can always play in the training arena to better grasp the concepts of the game.

Don't spend your gems ... Rather big part of the game is waiting for the chests to unlock. This is a design by the developers to make sure you'll keep returning to the game every now and then throughout the day to play a little. My strategy was to open all my silvers trough the day, but not battle, open my gold (or higher) over the night so I have a fresh 4 slots the next day to fight and win crowns to open the crown chest and it worked. So don't spend gems on this if you don't intend to "pay-to-win" ALOT.