Wow, I love how thorough this is! And the way you described each system feels very balanced already.
As for inventory, weight systems are certainly hard to balance, which is why I gave the grid system as an alternative. You can make each item take up multiple squares on the grid, and limit how much each item can stack. Here's an example from Mabinogi, which ironically does let you carry 50 apples, 3 swords, and a few logs at once due to number of squares in the grid (or how few squares each item takes up):
A weight system could be used on top of this, but mainly affect stamina, usually travel speed but maybe normal stamina too. So you can have a full inventory, but shouldn't always.
But everything sounds really cool so far! :D