Wordpress thumbs

I need a script for creating thumbnails in wordpress that will do a few things.

1: Work on both Wordpress and Wordpress:MS.

2: Give a url of a default image if no attachment is found.

3: Grab the first attached image of a post.

4: Be able to place code in functions.php and use php tags thoughout the theme. This will require the code not to give a error when being used over and over.

5: Must be able to define image sizes though each php call tag.

Will be more than willing to pay for a script doing this.