Too low humidity can be fixed with several actions. Misting more, contain the moisture with a partially covered top, adding a waterfall (although waterfall only raise the humidity slightly) and adding a lot of live plants. From my personal experience, live plants are really good at keeping the humidity level stable.
You can use a timer with virtually any light source and there's really no reason not to. A dimmer, however, can not be used with fluorescent light of any kind (unless you build your own or the Exo-Terra Light cycle unit).Also, if I do get a lighting fixture I'd like to have one with a dimmer or at least a timer. What kind of bulb should I get?
And most importantly, have a look at the end of this page and use the search. There are hundreds of threads on how to maintain humidity. Here's a good one from SledgeMonkey: