When I first starting writing I to was not sure if it was a good idea. It just takes sometime and a lot of editing to get better!
Goodness knows it too me forever! But whatever you do don't get frustrated and quit, just take a break and let your mind rest that's what I do.
Anyway to answer your question, it sounds like a good plot to start with now you just need to slowly build it up. Something I do is make a outline for each chapter. I do this so I know what I want to happen in each chapter and it cuts down on confusion later on. Keep the characters the same is a good idea too and if your wanting to change Kagome by all means do so. Me personally prefer a stronger Kagome any day!
Hope that helps you out some! Don't give up! It gets frustrating but don't let it get to ya!