"I like them."

When I was first learning Esperanto I was drilled to always use Ŝati as if it meant "To be satisfactory" hence Ili ŝatas al mi means: they are satisfactory, (or liked) by me. Thus, I like them. This translation goes against what I have learned elsewhere, & what keeps getting corrected when I use it as you did here.

Is "ili placas al mi" correct? It was not accepted.

Is ili related to li? As in: Could iŝi be used to refer to multiple females (as in the french elles)?