^^ Okay, since we don't have spoiler code in this forum I will put the "dangerous" part in little.1-2) Zelda has a speech at a moment of the game (unfortunately you can't see it anymore) explaining everything about Termina. She created this world with a wish to the Triforce, Termina is a land where you can find every thing you need and also a hidding place fo the Triforce. Link found the graals, Oni-Link his master and Ganon... the Triforce.
3) I don't have any timeline. I consider each game as a new facet of the Legend of Zelda. (Well, except for the cell-shading games in that sea-world which are obviously in the future.) The idea is not of me though, but I think it's an excellent idea ^^.
And for the roth games... they are the sequel of Alttp, put them in your timeline as such, but don't forget that they are not official
4) Time to Triumph
Congratulation for beating the game by the way. Glad you liked it. I guess we will see you again for 3T