Gas irons come in a wide range of sizes, and each has its own range of attachments variously allowing anything from a needle tip to a moderate sized chisel, some have a hot air attachment (VERY hot) and many can be used without a tip as a small blowtorch. The largest one I had was about equivalent to 250W of electric, and could tackle any of my modelling jobs. The only thing to watch out for was the exhaust from the side of the tip.
Rudders? Depends on the size. Mine were small-ish and relatively unstressed, larger ones I tended to build by other means, but is soldering large ones, tobyker has it right.
