The main thing I would suggest while you're setting things up is to figure out how you're going to do your air circulation. Air circulation is key to maintaining a healthy growing environment.
You need a way to draw in fresh, hopefully cool air and another way to vent hot, probably humid air. For input, I would try mounting some kind of window unit type air conditioner in one of the walls. You can usually find used window units online for like $100. Grow lights generate a lot of heat, but MJ likes the temp to stay below 80 degrees, so the ability to cool your space is very important.
For your exhaust, you need to get a 6" can fan and a carbon filter to go with it. Most folks buy vented hoods to go with their lights and these hoods hook up nicely to 6" ducting. You run ducting from the filter to each of your lights, up to the fan and from the fan, through more ducting, out of the room. Most people have their exhaust air going to their attic, crawl space or any other area outside the grow room. Exhausting your grow space not only helps control temps, but it also helps with excess humidity, which can cause all kinds of problems.
Now, I'll try to answer your other questions. First, I would really have to look at the two spaces you have at your disposal before making a smart decision on which is best. Off the top of my head, though, I'd probably go for the insulated space over the more bare bones one. In your part of the country, I don't think heat is that big of an issue in summer, but cold certainly is in winter. The more insulated the space, the easier it will be to control the temps at any time of year.
As to finding clones in the Portland area, I wouldn't be of much help, as I'm in Texas. From what I've read, though, it seems that most dispensaries sell clones to patients. That's the way it works in Cali and Colorado, though, so not sure if it's the same where you are. You could always order some seeds from one of the many seed banks on the internet. I've heard very good feedback on The Attitude, just to name one vendor.
Finally, you have the question of which method of growing is best. This is a topic that is highly controversial and as many growers as you ask, you'll often get that many different answers.
For myself, I've always grown in hydro and wouldn't do it any other way. This is at least partially because when I first started, several years ago, all of my starting equipment was given to me by a grower friend that was shutting down his operation. His set up used rock wool cubes in ebb and flow trays. I still use rock wool and ebb and flow for clones and vegging, but now I put my 4" cubes into 9" net pots, filled with hydroton pellets and use drip stakes for the flowering phase.
I find hydro growing to be exceedingly easy. As long as you keep all of your equipment clean and don't use any organic matter in your solutions, a hydro set up can be easy to manage and produce great results. As far as I'm concerned, soil is messy and makes it harder to dial in correct water amounts, nutes, pH, etc. Lots of folks around here seem to like soil growing, but it's just not for me. Bottom line, if you can afford to spend a couple thousand dollars all at once, I'd go with hydro.
I'll keep an eye on this thread, so let me know if you need any clarification on any of this stuff. I'm not an expert, just a guy who's done this a few times with good results. BTW, sorry for the wall of text, but you said you wanted info, right?