1. You can look at that via the menu Components->HikaShop->Discounts
There, you will see the listing of discounts and coupons. You can create new ones, edit them, delete them.
2. Sure
3. You can manage coupons in all the versions of HikaShop. In the commercial editions, you will get extra features related to the restrictions: You will be able to restrict the coupons to one or several groups of users, have quota, etc... However, since you're not planning on using the cart part of HikaShop, these features won't be useful to you...