1) what are elliptical leaf springs i hear 1/4, 1/2

That is 1/4 Elliptical. Notice there is only half an Leaf Spring. Used with some type of "link" suspension, all it is there for is to support weight, not side to side or "wrapping" motion.

3/4 Elliptical. Notice there is a full spring and half a top spring. In that configuration the top half leaf is there for drooping purposes. You can also set the top leaf to hold weight for added up travel.
And 1/2 Elliptical is your run of the mill leaf spring suspension.
Elliptical is a shape like an egg or oval. So a standard leaf spring is half the shape of an oval so that is 1/2 elliptical. Half of a leaf is 1/4 the shape of an oval so hence the 1/4 elliptical. And 3/4, you get it.
There is many many many types and ways you can configure a elliptical suspension. But we'll get into that another time.