1-2. I think Hivelist and Listnerds allow you to spend HBD for services -- Hivelist has various kinds of merchandise, and Listnerds is a reasonably good content promotion service for Hive -- although I would use the free version and test it for quite a while before upgrading.
None that I know of, BUT, because Leo has some bridges to Polygon and the Binance Smart Chain, I think there is a way to wrap HBD on both chains and trade them for other wrapped assets, and I think both Polygon and BSC has non-KYC access points.
20 percent interest -- the way I think about why hold HBD is because of yield on both sides of the market. I hold on to some Hive because the bear will give way to the bull someday, but HBD gives me 20 percent interest in savings day in and day out. Polygon and BSC through Leo projects also have higher yield farming options up to around at least 40 percent... a bit too out there for me, but, it is available...