Hello there,
1, SER6 MAX 7735 SSD specifications are M.2 PCIE4.0X4 (2280), a total of two SSD card slots, one SSD card slot can be expanded to a maximum of 2TB.
2, Yes, you can use NVME M.2 2280 key to upgrade.
3, if you need to clone and transfer SSD tools, you need to search or buy on the Internet.
Yes, the way you described replicating SSD data is correct.
Have a nice day!