createElement, insertAdjacentElement, for loop

I'm not super happy with the functionality. I've been stuck on the validation.

1. If a user misses a field, they get an error. However, if they correct that error, I can't get the newly created element to disappear. Any help there?
2. Similar to my first question, I can't get the field border to change if the user fixes any errors. I can get the font color to change back correctly, but not the border.
3. Because I'm using createElement to get my error Icons & error spans, when they get created, they're bumping the rest of the form fields. Initially I had them all just visibility: hidden, changing to visibility: visible. How do I avoid the content bump?
4. Again, sort of going off the question above, if a user misses a field multiple times, the submit button keeps generating errors over and over again. How can I only allow errors to show up once?