Webmasters need to know a bit of SEO,basic knowledge of stuff and must be dedicated to his work.
There are no shortcuts to success.
its not necessary that a webmaster should know php etc, cms like wordpress and joomla need next to no programming language,
But if you are dedicated to your work, and have patience and hard work, a bit of SEO will be enough for a success of any website.
Webmasters need-
1. Little bit SEO knowledge (link building and keyword targeting is enough).
2. Some basic programming knowledge, not necessary, but would help.
3. Hard work,dedication. Websites often needs several months to become noticeable in SEs.
4. Good hosting with good uptime and fast response.
5. Always remember that content is the king.
Dont need-
1. Extensive programming knowledge. wordpress and other opensource scripts are very easy to use.
2. Dont need to spend money on SEO campaigns,although it can be helpful,but not necessary.
3. Photoshop or graphic editing skills are not required at all. I myself am too bad in GFX. You can always pay someone to do a design, here at WJ many people would do a graphic even for free.