Grimrock

you've got to very quickly twice in a row to throw the course against teleport. The first hour deactivates the teleport. The second hour opens the door. You must do this using two characters.

Is there a way to get the gold key from below the grate ("eternal puller")?

On level 4 there is a "hide and seek" puzzle I'm not quick enough to do. Someone in an earlier post suggests luring a snail onto the plates but I don't see a room nearby where a snail spawns. Just before I get to the Hide and Seek area I have just beaten a large mushroom and there are 2 buttons and 1 of them spawns a teleporter but it is so brief that it's impossible to get in it. Any help on these 2 items would be appreciated.

Now just the teleporter to solve please.

I passed to the 3rd floor of the tower from above, then faced the "dodging" puzzle, saw the key in front of the head that is shooting lightning bolts but couldnt reach it (it pushes me away as im trying to come closer from any direction). Searching brought me a key that fit one of the door locks (west one), there was a lever (i used it but dont know what was happened), and this was a point that i stuck at for that moment. After some scoping i found rune button but again didnt realize what it affects. Then i tried to remove all rocks from the plates and - bingo! - the trapdoor in front of the passage was opened. I fell into it and found a way back to the previous level (opened stairs), but the trapdoor in front of the passage was still opened and blocked my way back to the second closed door, the key in front of the head and a puzzle that i havent solved yet ("You need light to travel in the darkness"). So the questions are: 1) what's the point in pressing the rune button? 2) how can i open the second door on the east side of the map? 3) how can i get back to the shooting head after passing the next level?