You can wash a wood painted house just the same as any other with a couple exceptions, Run a little weaker SH mix. I would start with a 20% mix in a small hard to see area and run a quick test. The key is to "NOT" let the mix dry on the surface. Do one section at a time so you can keep everything wet...
As for pressure, You can do a soft wash or conventional downstreaming pressure wash however, You need to run larger tips so they handicap the machine.
Whenever I pressure wash a wood painted home or Hardie plank sided home, using a 4gpm machine with 3000-3500psi, I run a 2510 tip for rinsing. You'll have full flow but much lower pressure.
I have done a ton of painted homes as I live in a semi-historic area. They are in most cases, easier to wash than aluminum or vinyl. You just need to exercise some caution.
Mike