1. Could I swap out the 16 GB M.2 that comes with the Lenovo, replace it with the MyDigitalSSD SC2 Super Cache 2, install the OS and apps on it and use it as the primary boot drive?

2. What’s the difference between the MyDigitalSSD 128GB Super Boot Drive and the MyDigitalSSD SC2 Super Cache 2 42mm SATA III 6G M.2 NGFF M2 SSD Solid State Drive?

3. How reliable is this M.2 SSD in comparison to a Crucial MX100 or a Samsung EVO?

4. Would it just make more sense to pluck the M.2 and HHD from the computer and install a 500 GB Crucial MX100 or a Samsung EVO?

Thanks in advance for any feedback / advice on this.

Hello,
When we have a 128gb ssd , the optimal partitioning could be like this ?
100 gb for windows and most used programs
20 gb for cache
8 gb for windows cache (like linux partition, if it works for windows?)

Do you have any suggestions ?

I was thinking 64gb as cache, no separate partition for the OS. That way you keep it simple with only one logical drive.

You could go that route but, IMHO, these drives have a wicked price point. I would favor 64GB for the OS and then the remainder as a cache, rather than 32GB for the OS.