Help me Swap my Computer Case

I’ve had my PC for 6 years now and I’ve noticed her slowing down a bit, and I want an internal disk drive so I need to switch my case, or just the case front. I’ve never built a pc before the most I’ve ever done is add 1tb of storage into my old laptop and I can’t remember if I activated the storage correctly. My Specs are as followed…
CPU: AMD Ryzen 7 5700 3.8 GHz 8-Core
Cooler: Thermaltake TH240 V2 ARGB Sync 57.05
Motherboard: Asus TUF GAMING X570-PLUS (WI-FI) ATX AM4
Memory: Kingston FURY Beast 8 GB DDR4-3200 CL16 x2
Storage: Kingston NV1 250 GB M.2-2280 PCle 3.0 X4 NVME Solid State Drive
Video Card: Gigabyte GAMING OC GeForce RTX 3070 8GB
Case: Idk
Power Supply: Apex AG-M 750 W 80+ Gold Certified Fully Modular ATX
Operating System: Windows 10 Home 64- bit
The things I am upgrading and need help with are as follows…
Add more 8 GB RAM; Just shove it in?
Swap my 250 GB storage to 500 GB if I can; how do I properly transfer the data from the 250 GB onto the 500 GB.
Swapping my case; how do I not mess everything up… also how much thermal paste is too much or too little?
Finally Upgrading to Windows 11; is it worth the aggravation and effort to install the update and disable all of its AI features?
Thank you for your time.