Hi Sam. I’ve made a very basic game in sugarcube that has it all except the health bar (it uses numbers). While the code is not commented, maybe you could use it as an example: https://janosbiro.itch.io/space-snacks. Get the HTML file and import it into Twine to see the code.
There are a few options for the health bar. Again my references are The Meter Macro Set by Chapel, the Health Bar sample code by HiEv and this example from the Twine Cookbook.
The money system is the simplest one, you just have learn how to use variables and the set macro, basically. For the skill system you can use this example.