With regards to mimicing the default style, I think you'll find the style guide in the SDK useful for matching particular colors and fonts, etc. You can find it in sdk\resources\styleguide:
As for improving the experience, I try not to fight what the CRM framework provides. I use the existing controls as much as possible and use supported javascript to smooth over the on-form details. If you have a specific requirement we can suggest solutions. The form events for onload, onsave, and onchange provide an acceptable level of feedback for almost all situations on a data form. What specific requirement do you have that requires more than those?
Hope that helps.