Can I / should I keep spices & dried herbs in the fridge?
Most fresh herbs do quite well in the fridge, so long as they're prepared appropriately.

I would not put dried herbs and spices into the fridge, especially if they're in a hard-sided container.  (unless maybe if you were in a really arid area)

There problem is that if you're in a warm, humid environment, you'll be trapping a little bit of moist air in there each time you use some ... which will condense in the fridge, which could result in rot for the herbs ... and I'm not sure what for the spices.

If you really wanted to pack them in the fridge, I would put them in a bag (vacuum bagged, if you can), and leave them there, with another container outside the fridge with enough for a month or two.  In this way there's less moisture trapped in there, and you're not opening it frequently.