Kiwimum, great to hear you made it to level 9. This is a pretty complicated dungeon if you don't know the exact route and I probably won't be able to walk you through the maze, room for room without confusing the hell out of you. But, if you go north through the entrance room and take an immediate right in the second room, then go south through a walk-through wall you will find a portal that will allow you to access the NE portion of the map. From there you should be able to wander your way to the room that takes you to entrance 2. Make sure to bring some bombs to handle the Dodongos. Let me know if this helps and let me know when you beat the game, you are close!!!.
Boommaster, to get the boss key for level 2, do the following: Go to the second floor and travel to the NE portion of the map. The boss key is in the room right before the boss. There are several blocks around the edge of the room. Try hitting the blocks with an item (boomerang, arrow, etc.). Keep an eye out for that type of block throughout the dungeons, many times you can activate them by hitting them with some object. Also, if you ever need help check my website (http://zeldafragmentedland.bravehost.com). You can download maps that give the locations of the boss keys and other items.