Hi Fred, welcome to the forum!
To answer a few of your questions, there are many places to shop for coral in the NW. Many of which happen to be sponsers of our forum. As for where they get them, I have no idea..lol
Do you need a chiller? well as I am sure you already know, thats a bit of a loaded question because it all depends on few different factors. one being lighting and also what kind of heat your pumps and such give off.
Are there places to get large tanks here? yup of course there is, this aint Siberia! lol Most of our LFS sponsers can get pretty much what ever you want. We also have a sponsor who builds acyrlic tanks.
Water supply - Depends on where you live. My TDS last night was 126 going into my RO/DI. But Oregon has several different types of water supplys and each one handles their water a little differently (for the most part)
Weather? most people would say rainy but I would classify it as mild. We have all four seasons here.
PNWMAS has monthly meetings and a few events, and frags swaps and such are common.
Anyways, welcome!