I love seeing threads like this pop up, it's always fun and inspirational to watch other people develop their games.
I love your idea and you seem to be quite good at art. To be honest I wanted to say that I think your older design for your character that you posted seems to fit your story better.
Making tests is the way to go. This forum is excellent for getting help and finding threads where people have gone through the same stuff, but often when I don't understand how something works in Construct I'll start a new project just to learn that one thing. It seems to help a lot.
Welcome aboard, and look forward to seeing more of this!