You don't need to fork out big money on rain barrels, I was just reading in the frugal forum about someone who got some discarded barrels from a car-wash free (USA). They held windscreen cleaner but a good wash got rid of that. Wouldn't use the stored water as drinking water though. I've seen several places that sell old food storage barrels. I've seen them for $10 locally (Australian). My father uses one as a rain barrel, he just directs the rain off his garage roof into it.

Same here... I don't currently have rain barrels, but I did when I lived in town. You can usually buy plastic barrels in blue or white that have had soap or food dye in them from industrial junk type shops or look in the paper. I know places up here that frequently have them...but no where in Seattle as I don't live close enough to you.

And lots of mulch! That really helps. My garden is exposed in full sun and I plan to mulch deep where I can.

Also, you might think of planting things that might provide late day shade for your plants, when the sun is hottest. Like a clumping bamboo... or a lavatera. Something that grows tall, doesn't cast dark shade, and won't take tons of water itself. Plant in the southwest or west.