I'm not very familiar with squarespace coupons, but squarespace doesn't really allow for much customization of the commerce. I did manage, for instance, to add a limiting checkout for another customer, but that was a minor modification. You can see it at work on my shop test.
I could probably make something similar for your first request, but the coupon codes would have to be manually added on the advanced code injection script, which wouldn't be too hard...
The problem there is automating anything. I'm really not sure what you mean there, by "no manual labor" and all, but I find it really hard to automate whatever with such a closed system as this squarespace commerce unfortunately is.
In any case, here there are 2 alternatives I haven't tried, that may suit you: https://answers.squarespace.com/questions/17702/can-i-sell-and-use-gift-cards-with-squarespace-commerce
Also I did notice Jason Barone asked that question over 1 year ago. Maybe he managed to develop something ( if you do go to him and find out a solution, please let me know! ).
I could find nothing on the developer docs to support this would be possible there. I still didn't have the opportunity to go on developer mode, but as far as I can tell, it's only good for customizing templates and it gives just slightly more and still much limited access to the locked in squarespace backend data.