quite possible to do all that.
they might be dull simply because a few arent working, so its best to chcek that. you will actually find that putting leds in wont make anything any brigter. on the back of the dials, there is glue sorta stuff, that prevents light shining thru so much.
if you can find leds that project light a bit better than some, that only shine light in one direction. i found that they are pointless because of this glue.

but my 2 cents would be just change all the bulbs to normal bulbs and see how you go.

like lan said, there are a few threads in the diy section on how to change the lights in your cluster.