The c_move instruction has two speed parameters, you need to use the second one, f.i. as follows:
vec_diff(temp,cover.x,my.x);
temp.z = 0;
if(vec_length(temp) > 15) vec_normalize(temp,15);
c_move(me,nullvector,vector(temp.x*time_step,temp.y*time_step,0),IGNORE_PASSABLE);
For the animation part you could continue as follows:
vec_to_angle(temp2,temp);
i = ang(temp2.x-my.pan);
if(abs(i) < 45) anim normal
if(abs(i) > 135) anim back
else
{
if(i >= 45) strafe left // should be left, I think
else strafe right
}