Minecraft – redstone device that can gather lava buckets hands off

You aren't actually powering the raised block in this instance, because... reasons. That block is receiving power from the torch (and would do something if it were a redstone device), but you're not powering it, which sounds strange and contradictory, but that's the best I can explain it. More critically, you're not transmitting power to the block the second redstone torch is in, as the block it's on is only weakly powered, and thus can't power adjacent blocks.

So in order to power the block, you need to feed a line of powered redstone into it, point a comparator or repeater into it and power that, or place a torch under it, like so:

although your basic not gate (which is what I think you're mainly interested in) is like so:

Note that the second torch is on the side of the raised block. This is important.

If Endermen take any form of environmental damage (fire, water/rain), they teleport away and lose all interest in everyone who might have hit them before. so if you hit them with a fire sword, they will start burning and immediately teleport randomly for a few times until the fire goes out. If no environmental damage is dealt, they will pursuit you until they kill you or you run out of range.

Enderman as well have the habit to stand still then teleport if you stare into their eyes then lose contact. This can cause them to teleport around frequently during battle, so try to look down at their feet. In addition the teleport is in all directions, so they could be above you or below you in a cave after a teleport, unable to reach you until you get out of range.

The easiest way to kill an Enderman is to use their size against them. Build a 3x3 ceiling at 2 blocks height so that you barely fit under it. Then pull an Enderman to this location and he will keep running against the ceiling, unable to hit you and unable to look at you, while you can easily finish him off. You can as well use natural ceilings (leaves, rocks) at the same height instead of building one. Use a looting sword for increased chance to drop.

If you have any form of teleportation mod installed, you can do the same in the End world, which will thanks to the huge amount of Enderman gain you pearls very quickly. If the dragon is still alive, things get a lot more difficult. Then you need to find a location where the dragon is out of range. In some End worlds this is possible, in others the island is just too small for that.