1. no idea, Tecware seems more keen in pushing the low-profile TKL
2. it will be a very unpleasant experience to de-solder the switches from the keyboard

So, let's see what you can do with your board ya.

5. While desoldered, make a foam layer for between the plate and PCB. Very time consuming but highly recommended.
6. Foam layer underneath your PCB. To fill in the void that might be creating some resonance. Did not do much difference for my case but YMMV. Also worth trying coz it's usually easy to do.
7. Change all switches! Might cost a bomb though if you go for the currently "in" switches like Holy Pandas or NK Creams, or anything from Zeal. Lol.

You can check the previous thread, pages 107-109, for my adventures in foaming.
https://forum.lowyat.net/topic/4538548/+2120

3.5mm EVA would be the holy grail if you could find it. I managed to compress a 4mm to 3.7mm and it worked for me.

Almost any tactile switch will do. As long as it is mechanical and has MX or box style stems. Buy a switch tester if you want to start exploring. There are some pretty huge kits available nowadays. For an extreme example, check out this 130 switch testers:
https://www.aliexpress.com/item/32894898620...earchweb201603_