This puts larger businesses at more of an advantage, who have more resources to deal with official registration type stuff. The poor man's copyright (mailing a copy of your work to yourself) needs to remain viable.
I don't believe that anyone has used the poor man's copyright in court and have seen a lawyer take the whole idea apart with ease.
For example, tomorrow I go buy a stack of double ended envelopes. I send them all through the mail at various times without sealing them. Not all will be usable but one or two will be viable. I take those ones and wait.
Then someone who I plausibly interacted with at some point creates something really popular. I take a copy and create an apparent early version. I then seal that inside one of my pre-stamped envelopes. I then try to take the other person to court, saying I showed them my early version and they have ripped me off. Given that such precedent fights are the only cases where such a copy would matter I've just reversed the entire system.
As to the database it would need to be public and have accessibility as it's top priority. I was thinking of a system where you simply send an email with your work to some address and receive a registration hash that must be included in your work.
Right now copyright doesn't require registration at all so my priority isn't screening or adding any substantial burdens. Allow registration at any point in the first year after publication by a range of methods, with no screening on registrations, and I think that's fairly safe.
"Every case" is probably a serious oversimplification. I know they do have to be actively defended, but minor cases of trademark use go unnoticed all the time, and I doubt that a trademark is considered abandoned simply because they miss one or two here or there.
Any substantial case then.
Realistically it's any case the trademark holder would be expected to be aware of. Any cases they don't pursue become part of the defence for anyone who chooses to violate their trademark in the future.
As for the rest, yeah, I was pretty much agreeing with you.