How much SEO work is there on one site?

I'm thinking of hiring a dedicated SEO person. But is there enough work for a fulltime or even just a halftime person if its just one site? I'm assuming the SEO person can't be an expert writer and therefore needs support personnel such as graphics or writers. I also have a web person to help with onpage tech. The tasks I see are:

1. onpage technical changes
   
2. keyword analysis
3. topic curation
4. outline creation
5. article editing
6. competitor analysis
7. backlink outreach

Lets say #1 takes a fixed time to get the site in decent shape and then only needs minimal support work. #7 could take an indefinite amount of time but shouldn't it be automated? The others 2-6 seem to be at most 10 hrs a week?