Orbweaver - keybind advice needed

Below is how I run an Orbweaver Chroma with a Naga Chroma for WoW Classic. (I also have a Blackwidow Ultimate, but I don't use it except to type.) In Synapse 2.0 (seriously, Razer, still no Synapse 3.0 support?), I changed the following Orbweaver keys:

• 01-05 --> QWERT
• 06-10 --> ASDFG
• 11-15 --> ZXCVB
• 16-20 --> YUIOP
• Alt key (the top thumb button) --> , (comma)
• Spacebar (the bottom thumb lever button) --> Escape

In Synapse 3.0, I changed the following Naga keys:

• Repeat Scroll Up --> [
• Repeat Scroll Down --> ]
• Sensitivity Stage Up --> Tab
• Sensitivity Stage Down --> ` (the apostrophe-like key below the esc key)
• 10 --> Alt
• 11 --> Ctrl
• 12 --> Shift

In Bartender, I set up 4 grids of buttons, each with 20 keys, organized in 4 rows of 5 keys (like the Orbweaver buttons), with an additional bar of 9 buttons all in one row. I centered one grid horizontally on my screen then put one grid to the left of that and one grid to the right. My fourth grid is in the bottom left of my screen. The bar of 9 buttons is below the 3 centered grids. I use my last bar as needed for miscellaneous buttons that correspond to random, unorganized keybinds. I keybound:

• the center-most grid to the corresponding buttons of my Orbweaver, without a modifier. This is where I put my main abilities that I click often.
• the center-left grid to the the same keys as above, but modified by the Alt key. When playing a hunter, this is where I put pet-related abilities and macros.
• the center-right grid to the same keys above, but this time modified by the Ctrl key. When playing a hunter, this is where I put my traps, misc combat abilities, and any macro variations of the abilities in the center grid.
• the far-left grid is again keybound to the same buttons, but this time modified by the Shift key. I put the misc abilities that I use out-of-combat, i.e. professions, here. I usually just click these though.
• the 9-button bar is keybound to 1-9 on my Razer Naga, and is reserved for my cooldowns.

Additionally, I keybind class-specific abilities (i.e. pet attack, pet passive, stealth, charge, etc.) to , (comma), using modifiers when needed. In-game keybinds I changed are:

• Move forward --> Up Arrow
• Move Backward --> Down Arrow
• Strafe Left --> Left Arrow
• Strafe Right --> Right Arrow
• Autorun --> ] (which is on my mouse now)

The beauty of this setup is that all of my movement keys now only require 1 finger (my thumb) rather than requiring 3 fingers for WASD. Although I normally move by holding both left- and right-clicks on the mouse (even with this setup), having this capability is important because strictly mouse-moving forfeits maneuverability (i.e. your ability to strafe, walk backward, etc.). It also allows me to keep moving while I use my mouse for other things, like moving things around in my bags, left-click dragging to change my view without running that way, etc.. Additionally, my modifiers are separate from my ability keys, so my clicking a modifier never prevents me from clicking an ability. The only things that shares a finger with my modifiers are cooldowns, which I never need to use a modifier with. I've used this setup for over a year now, and I've noticed few issues with it. The only things I have considered changing at this point are to change my Orbweaver spacebar from Escape to Tab (which is currently set to Sensitivity Stage Up on my mouse), then changing Sensitivity Stage Up from Tab to a button that I will assign to my mount (which is currently either Alt+[ or Alt+], I can't remember). I'm also considering keybinding Escape to either scroll up, scroll down, or both. All in all, this was the setup that made the most sense to me.

Wow thank you so much @WaNtEdAmErIcAn for all that detail! That was immensely helpful! I'd love to visualize your bartender set up if you ever get a chance to post a screenshot here of it.