My husband and I recently got our first two crabs - Dr. Samuel Crabson and James Crabswell - who are doing incredibly well! We have a 10 gallon tank, with deep coconut/sand substrate, two hiding caves, 3 dishes, lots of fake plants (for them to dig up ALL THE TIME), climbing gear, moss, plexiglass cover for humidity, heating pad at the back, etc. We just had a few starter questions from a few days of early observation:
1) Is it normal/healthy for Crabson and Crabswell to spend all their time together? It is certainly adorable. The first night they were on opposite ends of the tank and were quite isolated. Now they sleep together, follow each other everywhere. And most nights I find one of them -at one point or another- standing directly on top of the other one. I know they're social animals and this is most likely a good thing - just want to make sure.
2) What is the best time of day to take them out of the tank for a short time to get them used to us. I feel like when it's night and they're already out and active, I don't want to interrupt their routine or make them scared to do their thing. And during the day, it seems like I'd have to force them out of their happy hidey spots. Am I projecting too much? What would be ideal? What do you find works best? Also, when are they most receptive to being active outside of the crabitat for a few minutes?
3) One of my crabs is definitely too big for his shell - he's spurned the many shells we've offered (we've tried soaking them in some salt water). I feel like we aren't giving him the right ones, but we're a bit limited. Does anyone know of any good shell suppliers online (we don't have easy access to a pet or craft store at the moment)? Both crabs have shells that look like the one in this picture:

4) We were thinking of getting a heating moonlight to keep things warm and dimly lit in the evenings. I having trouble, though, figuring out a stand for the bulb - I'm looking for something simple, because our space is small. Any suggestions for the best bulb or fixture?
5) We got a piece of plexiglass cut for the top of the tank (the daytime light sits on top of it) and typically leave a very small space (a few milimeters) open for air circulation - I often worry it's not enough. How much ventilation is typical? Much more and we lose a lot of humidity quickly.
6) There is PLENTY of information everywhere that details WHAT/WHAT NOT to feed the crabbies, and I've been sticking to those rules pretty well. Unfortunately, I've been unable to find out HOW MUCH to give them every day. I feel like I may be putting out too much for two medium(?) crabs, but I don't want to underfeed. What is standard?
I think that's all for now. We are greatly enjoying our first week as crab-caregivers. They are fun and silly and the perfect pet for our situation. Hope to be in touch with you all in future!