Hej! Writing this from my phone so bear with me.
1 dollar is something like 7 swedish crowns
The entrance fee is about 90 swedish crowns.
Easiest & cheapest for you would probably be to buy a wrist band that allows you to go on as many rides as you want, I belive those are about 300 swedish crowns.
I can try to edit a more complete answer once I get on a computer but I think I covered the most relevant stuff
Edit(from phone) : those coupons you are talking about are all the same, different rides cost a different amount of coupons (1-5?) and i belive they are about 20 kr/each, maybe cheaper of you buy a little collection of them
2 day entrance + wrist band is 590 kr or something around there
Edit2: some parks in europe (ex europa park) gives you a free entrance + wrist band at liseberg if you've got their season card ( and vice versa)