Wordpress Modification

I'm looking for someone with a sound background in XHTML/CSS & PHP to help with modifying a wordpress theme for me. Things to be done:

1. Change the way the posts are listed/displayed on the site.
2. Change post title font size.
3. Add a repeat-y background image to sidebar.
4. Change navigation css (an example site exists so you can pull the CSS from it)

Please only reply if you are experienced with properly and successfully modifying Wordpress themes. I know moving the codes around is something anyone with a bsic background in CSS can do. But this is for a serious project that has to be right. Thank you for understanding.