Unfortunately, the Finds are the only thing you can reliably count, since that is a somehow "proven action" and theoretically "verifiable" in the logbook in the cache. All other actions (DNF, maintenance, cache hiding date, ...), can be done pretty simply without any consequences from home and it is more or less valid reason for a log (I really wanted to go out, but it was raining so I am logging DNF on this nice cache around the corner; I wanted to get rid of the maintenance attribute, so logging NM -- last cacher did not complain; the hide date is frequently faked, either deep in the past or to publication date, which neither is the date one actually did caching). Some people even change their DNF logs to the Find log when they finally find the cache.
I appreciate your ideas, but I don't think this is a way to go to modify existing stats to do all of this. For example, there is already the Hides tab, which could be extended with some of your ideas, such as a calendar of hides, maintenance logs, if you have enough of them.
With DNF it is more complicated. Not everyone logs them, because sometimes there are muggles around, sometimes you don't have enough time to search or you feel like blind, since you know this cache will be tough and you rather return later. I have one of these caches, where most of the people write that they had to come more than once, but for 280 logs I have just 18 DNFs.
