This laptop only has one M2 port for an SSD. Therefore no, you can't add a second internal SSD. You could replace the SSD with a larger volume drive, if you like. And as someone noted, it does have 2 USB 3.1 ports on the outside that you can use to plug in an extra hard drive if more space if needed.
Two RAM slots. Only one is used from the factory so you can add a second 8gb to max it out at 16gb if you like.