SEO For WordPress Website

I am looking for someone to help me increase my website traffic. It currently runs at only 400 hits per month.

The website already has an SEO pack installed and Sitemap with all the relevant information on there and its been running for nearly 2 years.

I am looking for someone to:

Add H1 Tags
Look at other H tags and updated
Error page to be removed
SEO on each page examined and updated.
Increase page rank from 2
Link building

I already undertake basic SEO on the website and blog every week. I use software such as SEOMOZ, Link-Assistant, PRWeb, Hubspot, Koozai etc.

Please can you let me know:

1. How long to undertake the SEO I would like doing?
2. Examples of other SEO campaigns you have undertaken and what position on Google the client is at?
3. How much to help me achieve a good position on Google for the keywords Website Design.
4. What SEO software you are proposing to use?

Please note I am only interested in ethical SEO link building.

Many thanks

Grant