1. Is it possible to create an arbitrary-level PC from scratch? I'd like to be able to try out my encounters with a 'dummy' L2 PC to check the difficulty is right.
I mean, you could just set it up so the module gives you enough XP to reach level 2 on the ClientEnter event or a trigger on the ground. Could then save that character and load it for future testing.
There's also mods like Pretty Good Character Creator that let you do stuff like this, but pretty easy to script yourself for something as simple as just hitting level 2 (and good learning opportunity).
2. My buddy is going to be playing solo with me as the DM, so what is the best way to give him a couple of henchmen? Can I assign them to him as DM, or would I need to script it in through dialogue?
Script it, but doesn't have to be through dialogue. Could even just add them as soon as he logs in or crosses a trigger.
3. Is there any way to create a totally pitch-dark area, such that without dark vision or a light source, the PC wouldn't be able to see anything? I've tried turning the darkness down as much as I can in the area properties, but even with a L1 human PC, the light level seems to adjust so you can still see. (I want him to be getting nibbled by spiders in the dark ... ;-) )
Could do something like apply a Blinded effect if you're particularly cruel, but that also means spellcasters wouldn't be able to cast on anything.
Maybe apply a bunch of overlapping Darkness visual effects scattered around the zone (but without the actual Darkness effect -- theoretically should kill all the light).