1. That doesn't sound normal. There shouldn't be any reason for torches thrown to the ground not to give off light. Assuming you're using a drop lit torch kind of mod.
2. As you noticed, the lava switch opens the panel that has the button that opens the gate.
The second switch inside the miners' area opens the panel.
The switch out on the main level opens the varla cage.
It probably wasn't made entirely clear, but the miners were trapped by the spiders more than anything else. They should have explained that somewhat. They didn't feel as though they could escape without help, especially after Bites' party of relic hunters was all killed. They could come and go freely, but think of it as a security measure on their part. Anyone willing to go to the trouble of getting them out is probably friendly.
The Nenyond Twyll doors have a use later. I won't say more, but you're certainly not done yet. Expect a visit soon
