1. Yes, instructions in Service Manual 2. Yes 3. Internal M.2 NVME SSD,no external case; any brand you prefer. Avoid cheap "no name" brands. 4. Yes, depends on how you want to do it. Image existing SSD or clean install of OS and apps on new SSD 5. If BIOS is set to RAID, change to AHCI before installing new SSD. Do it exactly this way: Open Cmd, run as administrator Copy-paste this command, which will start Windows in Safe Mode the next time you reboot: bcdedit /set {current} safeboot minimal and press Enter Restart PC and tap F2 to enter BIOS setup Change SATA Operation mode from RAID to AHCI Save the change and exit Setup; Windows will boot automatically in Safe Mode Open Cmd again, as above Copy-paste this command, which will start Windows in Normal Mode the next time you reboot: bcdedit /deletevalue {current} safeboot and press Enter Reboot and Windows will automatically start with AHCI drivers enabled. Now you're ready to replace SSD. 6. If you plan to image the old SSD, rather than a clean install on the new one, you can use Macrium Reflect (free) to create an image and save it on either an internal HDD, if installed, or on external USB HDD. Include all partitions on the current SSD in the image. Be sure to set the option to validate the image when you're ready to create the image. If necessary, increase the compression level to Max to save space on the drive where the image will be stored. Also use Macrium to create a bootable USB stick you'll need in the next step. Once image is created/validated, remove old SSD and set safely aside. Swap in new SSD. Plug the Macrium USB into PC with power fully off. Power on and tap F12 to open the menu. Select option to boot from USB. When it boots, you're ready to copy the image from wherever you stored it onto new SSD. This time, move each partition one at a time, saving the C: partition for last. When you move the C: partition onto new SSD, look for the option to increase its size to use all free space that's available on new SSD.  Only the last partition moved can be expanded, so that's why you save C: for last, so it will include all the extra space on new SSD. 7.  If you plan to do a clean install of OS and apps on new SSD, change BIOS to AHCI with current SSD installed. Then swap in new SSD and use a bootable USB created with the Microsoft Media Creation tool for either Win 10 or Win 11 to boot PC and run the clean installation. 
I have an XPS 8940 with a 256GB SSD as the main drive. (#6 in image below). I'd like to swap it out for a 1 or 2 TB SSD. I'm familiar with adding/swapping regular HDDs, but have never done it with an SSD before. Thanks for any help. EdB   [IMAGE]  
XPS 8940, replacing the SSD?