row
var n = index - thisComp.layer("START").index - 1;
var gapX = 180;
[190 + n * gapX, 360];

grid
var n = index - thisComp.layer("START").index - 1;
var cols = 4;
var gapX = 230;
var gapY = 145;
var origin = [295, 215];
var col = n % cols;
var row = Math.floor(n / cols);
origin + [col * gapX, row * gapY];

controls
var ctrl = thisComp.layer("START");
var n = index - ctrl.index - 1;
var cols = Math.max(1, Math.round(ctrl.effect("Columns")(1)));
var gapX = ctrl.effect("Gap X")(1);
var gapY = ctrl.effect("Gap Y")(1);
var origin = [245, 230];
origin + [(n % cols) * gapX, Math.floor(n / cols) * gapY];

rotation
var n = index - thisComp.layer("START").index - 1;
var step = 10;
n * step;