2G 1997 Eclipse GSX auto - TCU questions

[jacobdsm7]

I’ve searched through the forum, but search results are only as good as the input—and at this point, I don’t know what I don’t know. So I apologize if this is a well-documented topic that I’ve missed.
I recently picked up a 1997 Eclipse GSX AWD automatic (W4A33) with a snapped timing belt, and we’ve decided to go through the car from front to back and rebuild it properly.
The block and head are currently at the machine shop, and I’m now looking at the next steps for the transmission and drivetrain.

Transmission Build​

My plan is to send the W4A33 out for a complete rebuild, most likely to Darren or IPT. I’m still deciding between the two, but either way, the goal is to have the transmission built correctly rather than waiting for the stock unit to become a problem.
The car is being built around an FP Green, GSC S1/268 cams, and pump gas/E85, with a target of roughly 450–500 AWHP. While I don’t currently plan to push it much further, I’m trying to build the engine and drivetrain with enough headroom that 600–700 HP isn't automatically another complete rebuild down the road.

W4A33 / TCU Control​

This is where I’ve started to pump the brakes and do more research before sending the transmission out.
I’ve read several discussions suggesting that once these cars start making 400+ HP, the factory TCU and the way it controls the transmission can become a concern for transmission reliability/longevity.
Is the stock TCU actually a problem on a properly built W4A33 at approximately 500 AWHP?
If so, what are people currently doing for transmission control?
I’m planning to use a Haltech Elite 1500 for engine management because I also want to install a Haltech UC-10 dash. Ideally, I would like to integrate transmission control into the Haltech ecosystem rather than adding several unrelated controllers if that is realistically possible.
Has anyone successfully used an Elite 1500 to control or interface with the W4A33?
If the Elite 1500 isn't capable of fully controlling the transmission by itself, what is the preferred setup?
I’m specifically interested in controlling:

• Shift points
• Line pressure
• Torque-converter lockup
• Manual gear selection
• Potentially paddle shifters
• Any engine/transmission interaction that can improve shift quality and transmission longevity

Paddle shifting is something I'd really like to incorporate if it's practical. It isn't a requirement, but I think it would be a very cool feature while still retaining the automatic.

Rest of the AWD Drivetrain​

Since the car is already apart and I'm approaching the build with a fine-tooth comb, I'm also considering rebuilding/refreshing the:

• Transfer case
• Rear differential
• Driveshaft/carrier bearings
• CV axles and boots
• Wheel bearings/hubs
• Engine/transmission mounts

Is there anything specific in the transfer case or rear differential that should be upgraded at the 500 AWHP level, or is a proper inspection/rebuild with good OEM-quality components sufficient?
The goal isn't to build a dedicated drag car. I want a very clean, reliable, street-driven 2G that can make around 500 AWHP, retain A/C and good street manners, and occasionally make some passes. I'm willing to spend the money now where it makes sense rather than repeatedly tearing the car apart later.
For those of you who have actually built and raced W4A33 cars, I'd especially appreciate your experience with:
Stock TCU vs. aftermarket transmission control, built W4A33 configurations, Haltech integration, paddle shifting, transfer case/rear differential upgrades, and anything you wish you had done while the entire drivetrain was already out of the car.
Please let me know what I'm overlooking. I'm trying to learn as much as possible before ordering parts and sending the transmission out.