Ok so to answer your first question it's a easy concept to see but hard to understand :/ It's just a feeling that you get by playing and which lead you to see big move that you want to play. It's not a big deal if you don't see exactly which move, it's more important to see the location of the move more or less.
But all that will come with some practice :)
I really encourage you to play on the site I gave, it's a good one ! :D
For the glossary, I don't know, I mostly learn that by watching and reading stuff about Go :)
I hope that I answer your questions :D