I'll be road tripping this summer in Oregon and I was planning to bring possibly 3 handguns.

One pocket handgun, one full size handgun with 15 round mags, and one .500 S&W revolver.

As I understand it, I won't be allowed to CCW in Oregon with my MO permit (no reciprocity).

1. What other gun laws should I be aware of? Can I at least keep a loaded handgun in my vehicle with me?

2. What areas of Oregon and/or Portland should I definitely try to avoid for safety reasons?

....And anything else I should be aware of?

http://www.oregonfirearms.org/faq

Pay attention to the areas where open carry is not allowed without a ccw. Multnomah county, tigard, Salem, etc. this applies to a vehicle in certain cases.

And you won't really find places you need to avoid. Enjoy your trip!

Here's a crime map of the Portland area: Crime Map - Portland Area