Having read the FAQ, there are still some things that I'm not totally sure if I'm doing it right.

So I've acquired a sub-adult female emp 3 days ago. For the first two evenings, she was always exploring around continuously. From day 3 and today, she seems to have kept to herself since I haven't seen her out of her hide.
I know that at least 3 out of 4 crickets had dissapeared since I gave them saturday and yesterday (she took the rosea's share since she didn't want to eat). It's a lone male cricket, so I doubt anything bad can happen if I leave him in there overnight.

I have two hides, one of the hot side and one on the cool side. She's been in the cool hide for 2 days now, so I wonder if the heat generated from the infrared bulb is too much. Since I've had it, I didn't turn it off since it seemed to help with the boosted activity and much needed heat and humidity. Is it right to leave the IR bulb on 24/7 or should I close it at night ?

When it comes to keeping the humidity, I dump a tall glass of cold tap water and try to moisten the tank evenly. Could it be that the water is too cold for her comfort ? And exactly how often must I add water per day or week ?

Is a thermometer and hygrometer necessary with all that I'm trying to do ?

I have the odd feeling that I'm doing it all wrong... I'm thinking of buying a new tank (with a screen top) and try out the false-bottom technique in order to have less problems to keeping the humidity. When this current emp tank dries up, I could place my rosea since the current kritter keeper seems small as her half-log hide is occupying half of the entire keeper.

My apologies, I tend to be "panicky" with new situations. I really hope you good people won't mind helping me feel less "silly".

Apparently, that lone male cricket was actually female. It popped out of hiding when I added some water when I thought it looked a bit dry yesterday and caused a tiny flood in the middle of the tank. The scorp didn't seem to mind all that much as she made her rounds on the tank and finally bumped and caught that naughty cricket. It was my first time witnessing a scorp eat before my very eyes. Quite amusing as she has her mouth full and just keeps on her merry way accross the thank.

Right now it is still slightly soaked, so I doubt I'll need to add anymore water for a few days. I'll need to get into the habit to actually feel the substrate before adding water to not flood the tank, wouldn't want my girl to drown. One thing I'm actually wary about is stressing the scorp enough that it gets out of its hide/burrow and perceives me as a threat and decides to sting. Since I can't recall if I've ever been stung by a bee or wasp, I have no idea whether I'd get an allergic reaction or not.

And while that female cricket was around, say that she laid eggs and now that I've flooded the tank by mistake, does this mean any possible eggs laid won't make it ? I wouldn't want a bunch of pinheads in there. I'm fortunate I never experienced that in my G rosea's tank since females often attempt to lay eggs despite the substrate being bone dry. *Knocks on wood*

Anyways, so far so good.... I make a few "newb" mistakes here and there, but I'm getting better

A flood won't hurt your scorpion. They can survive being submerged for days.

I've also never heard a reliable report of an allergic reaction to scorpion venom (for one, it doesn't have the histamine that makes bee venom an allergen, and it's possible to be allergic to bees or wasps but not the other (or both)). Not only that, but stings from emps are few and far between.

If you DO get pinheads, just keep the water dish full (a lot will hop in and drown) or put in a drinking straw with a plug at one end (they'll hide in it for easy removal).

Since I have no idea how old my emp is, given it's a sub-adult, does it mean it's one molt away from adult ?

What is the general time lapse for a sub-adult to molt to adult when kept in optimal conditions (good warmth and humidity plus weekly offerings of food) ?

And last but not least.... would a large kritter keeper be enough to keep it there as opposed to the 5 gal glass tank ? The large KK is slightly smaller from what I can see. It's something I would like to try out since my g. rosea seems happy in the KK since she's her usual "pet rock" self.

I really need to get a digi cam because there are some amusing moments at times. A few nights ago... she had so much trouble catching a couple of crickets as they kept hopping out of reach as she approached them. Took her about 15 mins before she finally nailed one.

Yes, it's one molt away. I'm not positive how long you have until adult, but I'd guess less than a year.

The large KK should also work - I have a single female in one right now.