Click the "Load Example" drop-down menu in the bottom-right corner.

It emulates the computer that runs Voyager 1.

I'm not sure I understand the question.

This was common back then. The PDP-8 had eight primary instructions, although one of them was multi-purpose. This helped keep the hardware simple when we didn't have ICs.

RISC isn't about having a small ISA but about a regular, orthogonal instruction set.