I'm a bit stuck at the moment with trying to create an in-app purchase for in-game currency. I've created an action with the reward for the coins, but I'm not sure where to go from there. Can anyone please help me out?
You can't. Plus, if you are offering IAPs for in game currency, you will need a way to restore those purchases on iOS, which you can't do for currency.
It is possible. I have already answered this question a few times. Please search the forum, you should find an answer for that.
I don't mean to be helpless but I can't find it in the forum. Could please you point me in the right direction?
Of course you can do this. Just make sure everything is setup correctly. If Apple rejects you the first time then it seems impossible to turn it around. Void jumping has an in-app purchase for gems and it works perfectly fine.