Hey, would love to help you out, but since I'm the dev, it would kind of defeat the purpose ;)
If no one responds here, maybe you can try asking in the Discord and we actually get a discussion going.
For that last one though (i.e. the first secret), I can tell you that it was a choice near the beginning, but it's also something you might not like anyway.
Right, replays don't count for unlocking anything or gaining any stats and there's no way to change that.
I should probably alter that bit of text for replay mode, but otherwise changing every single stat/unlock to be different between a replay and in-game events would be a nightmare.
Thanks for pointing it out. I'll think of a way to make it obvious.
On the plus side, now you know how you missed that one :)