HCA: Hermit Crab Association

I am new to the whole crab thing and have a decent amount of questions I'd love some clearing up on. First- substrate. I've decided I'm going to go for the play sand and coconut fiber mix, but have some questions on how to go about it. I've read that its good to mix the 2 together, but I've also see...

I am a bit of a beginner to this and have been using a tank heater on the side of my tank for about a week, and it does not heat up the temperature to save its life. I've been wanting to purchase some heat lamps to use for heat and lighting, since it is quite dark in my room, and want to kill 2 bird...