[onewhippedpuppy]

John, if you're going to wait to re-plant anyway, why not just Round-Up the entire thing? Spray several times to keep everything dead, you can till whenever you want. Even when the pros come in and re-sod they Round-Up first. I believe it kills everything to the root, as opposed to simply taking the top off.

If you'll be re-planting, the sprinkler is key. I think that's a good call, because no doubt you'll re-plant during the only Portland dry spell in the last century. At least that's how my luck goes.

As for the soil treatment, seek out your county extension office. They typically do soil testing for a nominal fee, and will then advise you on what to add. Much better than simply guessing at what your yard needs.

Considering your situation, I would also find a good local lawn/garden store with employees that know their stuff. Typically they will carry products optimized for your area and can tell you when/how to apply them. Having someone that I can ask questions is invaluable, as I'm still learning about this stuff as well. This is my second spring in my house and I've taken my yard from crap to pretty darn nice, and I started out knowing nothing about proper lawn care.