You said that you want to be able to slip in into your pocket? How important is this?
Your two choices are a dslr or a point and shoot.
A point and shoot is going to be smaller and cheaper. Its image sensor is going to be much smaller than dslr. A smaller image sensor means that the photo diodes are smaller. Each photodiode creates one pixel in the image. More photodiodes crammed into a smaller sensor means that there is less area to absorb light. this can cause a noisier image, among other quality problems. If your husband wants to grow with the camera, make sure it has manual controls. This is important once you start learning about exposure, aperture, shutter speed, ISO, white balance, etc..
A dslr is going to be larger, but it will take better quality images, and you can change the lenses. The sensor is larger, and the speed is faster. They have a view finder that allows you to look through the lens.
Check out this site for some more info. I dont always agree with Ken rockwell, but he does a good job of explaining in layman's terms for people just getting into photography.
Recommended Cameras
once you learn some about photography, check out the strobist site for learning about off camera flash
Strobist
also, once you learn how to use manual controls, and are ready to move on to composition, google "the rule of thirds"
Good Luck!