The upgrading of storage part, it's all depend on the SSD thickness and compatibility with the MOBO. Mostly, all mobile 2.5 inch SSD models come with 7mm thickness, Larger capacity would be thicker, as with most manufacturers.
Just a suggestion, the pick of the SSD, it all depends on your fund, because SSDs are costly; however they are worth every penny. The variation between cheaper SSDs and more costly ones that have similar capacity is their write speeds. Costly ones are usually 540MB/s write speeds while inexpensive ones go up to around 250MB/s write speeds only. Read speeds however, are the same.