SEO and Magento development, with commission

We are based in New Zealand.
We sell packaging products online, eg: tape, bags, strapping, food bags.
Our goal is to become number packaging company website in New Zealand.

Our platform is built on Magento.
Sales target 10,000 per month or more.

Currently monthly sales approx $600 / per month

I'm looking for experienced Magneto web developer / SEO specialist to do the following.
1) Monitor Google analytics and understand site traffic behavior.
2) Improve site content to increase sales.
3) Correct any mistakes on the website.
4) Work on SEO to bring organic traffic to the site.
5) Weekly report on work progress and site analytics.

Fixed wages will be paid per month.
A weekly commission paid on all online sales, the percentage is negotiable.

To be successful in this positions, please share your experience and technique you will add value in this position to increase sales on our website.