as said, a 30W iron will be ideal.
I've also got a gas iron, (that refills with lighter gas).
that's because I do a fair bit of soldering on the move as well. (it's formed an essential part of the gear I use when doing PA sound and such cause I can quickly fix any broken speakers or leads etc, I've also found it reall useful when working on electronics in the car or something where it's a bit more difficult to get mains electric out to the street).
to be honest soldering is one of those things that'll just come given practice.
as for the recommendation for the sponge to clean the bit, I'd almost say this was essential, I never used to use one, but when I did it made the whole opperation ten times quicker and easier.
basically if you have a nice clean soldering bit, and tin it a bit with solder first you should find that you don't even need to hold the iron on the components or wires for too long.
if you have a dirty old soldering bit, that's grey, or black, with lots of bits on it, and bits of the resin core coating it and such then it doesn't dissipate heat as effectivly and you need to hold the iron onto the work for much longer and thus have a greater risk of damaging components or getting dry joints.
