Answer
$4$, $(-4,0)$, $(0,0)$
Work Step by Step
Given $4p=4$, we have $p=1$. With the vertex at $(-2,-1)$, we have the parabola as $(x+2)^2=4(y+1)$. At $y=0$ (line across the focus), we have $x=-2\pm2$. Thus the length of the latus rectum is $|4p|=4$ and the endpoints are $(-4,0)$ and $(0,0)$
