Depth != more stuff. It reads like you want to throw everything alongside the kitchen sink at the game and I didn't finish reading, tbh, due to how you are asking about depth I felt I read enough.
I would focus more on a unique element of your game to flesh that out instead of trying to make everything seem fuller and have depth through adding things.
Think of it like an orchestra. You don't want every instrument to have a solo at the same time with the mix on each front and center trying to fight other instruments for the listener's ear. Heck, not every instrument needs a solo, depth or a reason to be there. Pick the one thing that makes your game stand out and use that for a solo and use the other instruments are there to support the arrangement without getting in the way.
Take the Souls series. There's not many weapons, not many attack combinations but the depth of the combat revolves around the ebb and flow, the dance between player and enemy, the precise moments of pressing a button to make a difference and not the number of times you press them.
Again, I didn't finish reading it all but it sounds like you just want a "lot" of things and that's cool, but don't fall into the trap of thinking more stuff is more depth.
Just my .02 I know it's a tactics RPG but I'm more on the side of streamlining core systems that are unique to your game and everything else acts as support.