Yes, this is a great way to expand capacity and performance. If two or more Tempo-X, X4+4, X8, X4i, X4P, E4i, or E4P cards are installed to the same machine they must all have the same firmware version to avoid conflicts.
Unfortunately, not. The driver was written by the 3Gb SATA controller chip maker, Silicon Image, and they no longer maintain the macOS driver for this chip.