You could pull off most small electronics soldering with a 15w iron if you wanted, I personally like to use a 25w. But yes, the 30w will be fine too - just don't overheat the components by keeping the iron on them too long. Putting alligator clips on the wires between the solder point and component as heat sinks can help tremendously.
Its easiest in my opinion to use the smallest gauge standard rosin-core solder I can find, right now I'm using .032 diameter. It melts quickly and sticks to most metals well.