Does the cart work with both NTSC and PAL systems
Yes, the cart will detect the type of N64 it's booted on, and change TV modes accordingly. It will also, by default, start software with this region.
What about stuff that's not from my own region?
If your N64 is NTSC, PAL software will either autodetect and run fine, or show a region notice. Same goes for the reverse. There's also an option to force software to run in the opposite region.
NTSC console: PAL software defaults to 50hz, can be forced to 60hz. NTSC color signal.
PAL console: NTSC software defaults to 60hz, can be forced to 50hz. PAL color signal.