Hmmm… The plot of the first one has nothing to do with the second. But you do get a lot of world building and some characters are properly introduced in the first.
I guess you should play the first as well if you want the best experience. It’s also a good game, though the puzzles are a little more… frustrating. But it’s nothing a good walkthrough can’t solve :)

Nah. Same setting and all, but story is mostly unrelated.