If you have the time, swing by Miller Brothers as well if you've never been - about 20 mins from Sid. Miller carries some nice stuff, has a bar (!) and is cool just to check out. And of course, H. Stockton...but you probably knew all that.
The painting itself - haven't seen anything older than like 1940s or 50s in that style & color combo, when the pacific islands became popular after ww2. Most is more recent. The stretcher does look older tho. I actively hunt tiki / mcm / etc and cannot see it being 19th c...mainly because no one was doing it then.That said, I totally would have grabbed it as well!
Nope - only letters / first class stamps. The last price increase was originally supposed to be temporary; the USPS tried to make it permanent but they were denied and had to roll the price back to the pre-increase rate.