Below is a Idle Kingdom Clicker Full Map that you can used to find the locations of different things without having to explore a bunch of times and make your own. For the most part there doesn’t seem to be a lot of locations to choose from especially around the outer edges. After you have reset a couple of times you will unlock the Library which is used to collect Science passively.
Your going to have to play quite a few times to get your score multiplier up there high enough to unlock a lot of locations at once. When getting more and more temples that raise your reset score you will start to multiply which will make your score very big after awhile. One things to remember is that it doesn’t matter which order you claim the temples as you will get the same number no matter which one is first or last to unlock.
There is no end to the game as you can keep playing forever increasing your score letting you build more faster on your next play through. The more temples you get in a run the better your score will be when it comes to resetting. It might be better to wait awhile to unlock more temples than to just take what you can on the fast earning tiles.
The developers makes it seem like he could come out with an update with more content any day now, but this seems to be not the case as the game has been released for awhile now without any new content added.
When it comes to how long you going to play I guess the furthest you could go for goals is to unlock every temple in one playthrough which would take a lot of time to accomplish.