I’d be happy to give you some pointers about writing characters.
We often discuss characters in oue Writing Excuses podcast. For example some episodes from Season 1 that may be of use as you write your characters include:
Or just search for episodes that have the tag Characters
If you’d like to see how I developed my characters in MISTBORN, you can go to my website and have a look at the Mistborn annotations. These give you my thoughts as I wrote each chapter, including how I developed my characters.
I think that these resources will answer many of your questions.