#1
I want to throw some lighter strings on my Ibanez RG, but have never done so before. Do I need to worry about anything before I make the switch or is it just a matter of adjusting the spring tension in the back of my tremolo?
#2
It might need a truss rod adjustment when you're done and you might want to lower the action. It depends on a lot of stuff you're not telling us.

Also, if you have an Edge trem, make sure you don't adjust the action while the strings are under tension--that will ruin your knife edges.