Who knows! On average in June in Portland, it's high of mid-70's and low of 50's. While there's a good chance we might be in early summer there's always a chance it could rain. We recommend packing your raincoats and a light jacket.
If they're not on the invite - unfortunately, no. We want to keep this celebration very intimate and strictly to our close friends and immediate family.
Unfortunately, no. While we love our nieces, nephews and little friends we want this to be an adult gathering for all invited.
For out of town guests, it would certainly make exploring outside the city easier but within the city limits there is pretty decent public transit via TriMet - offering buses, light rail and street car. Ultimately up to you and how much you want to explore during your stay.
Whatever makes you feel comfortable, we don't care! Casual!