1) I recommend melting in a wax lube into the joint. Floor wax, carpenters wax and SnoSeal all work (in decreasing order of effectiveness).
2) IMO, Opinels handle better with a bit of tension on the pivot. If yours is too tight for your liking, stick the largest flat head screwdriver you can find, put it in the slot against the inner collar and slowly twist the driver to open up the pivot a bit. The Opinel is, by design, a friction folder and a free pivoting Opinel is more likely to bite you.
3) The traditional way to open a stuck Opinel is to tap the butt end of the handle on a hard surface to pop the blade open a bit. This isn't needed for a well adjusted and lubed Opinel.
4) If you really struggle to open an Opinel either due to a lack of thumbnail or weak grip, I recommend using a rasp to file in an "easy-open" finger groove. Google for "easy open jack knife" to get an idea.
5) The Opinel is a traditional knife and like the vast majority of traditional designs, has no finger guard. It's meant for cutting, not stabbing. Other traditional with this feature include sodbusters, nearly all slip joints, the Buck 110 to name a few. In Scandinavia, the difference between a child's knife and normal knife is the guard or lack thereof.
6) I wear XL gloves and prefer the #9 for EDC, although it is big enough that it carries better in my rear pocket. At this size, the Opinel 9 is really a large traditional and like all large traditionals that lack a clip, you need to figure out what kind of carry works for your life. I *HATE* belt holsters and I find these knives too big for front pocket carry. I run a seam up the side of my right rear pocket and find this works best for me. I'm carry a heavy 110 today and don't even notice I have it on me. YMMV territory.