Stay away from the pressure washer. Not the right tool, and you really
don't want to force water into all the fissures in the wood.

Mechanically removing the paint (scraping, etc.) is the way to go. And
you're going to want to patch the areas where wood has been lost to rot.

The method an acquaintance of mine uses is good, I think: before
patching, he primes the wood. Then the patch goes over primer, which is
much more likely to stick well. Be sure to force the primer into all the
nooks & crannies.

And be sure to scrape out all the soft, spongy wood first.

Thanks, that sounds like good advise. What is the best stuff to using
for 'patching' up rotted out/removed wood? Is a silicon caulking good
for that?

Cheers.