Hi,
1. You will find similar price display options in the display tab of the configuration. These are the ones used on the product page.
2. You need to understand how that works.
You always enter the unit price.
So if you enter price/2 and a min qty of 2, and no prices for 3 or 4 quantity, if you order 3 products, it will display a price of 3*price/2. For 4, it will be 4*price/2.
If you want to add only a fixed discount of the amount of the price of the product for quantities above 1, you should instead create an auto loaded coupon with a minimum quantity of 2, the product selected, a flat amount entered and the "Coupon percentage applies to product only" option activated in your coupon options.
That will add automatically the coupon during the checkout.