SEO for our Corporate Website (STRICTLY white-hat methods)

We are a Singapore-based company and require SEO expert in optimizing our new website in the top 3 (or 5) ranking for Google, Yahoo! and Bing. This newly revamped website (we had outsourced the design to a creative agency previously) is not optimized yet (using 'customized' wordpress) and I am currently using plugin like SEO by Yoast to manage on-page SEO. However, as the website itself is quite massive (with quite a number of pages) and requires some tidy-up for SEO hence, we decided to outsource this project. I had already came out with a list of keywords for our different categories to be ranked and the competition of these keywords are mostly Low (only a few Mediums and no High) after an analysis from Google Keyword Tool. We are operating from a corporate point-of-view therefore only white-hat, ethical and Google-authorized methods are allowed for our SEO (compliant with Google Panda and Penguin for example). We STRICTLY FORBID BLACK-HAT SEO methods like article syndication, link farming etc. A SEO proposal consisting of the methods used, components involved etc is required. The challenge of this project is to maintain a corporate professional image (over the website) with SEO at the same time hence, you can only edit the content/ article heading etc accordingly to our guide and not accordingly to the keyword you are focusing (simply by changing the text for example) as we need to maintain a flow and consistent concept within the website. SEO copy-writing will be needed if necessary. Meanwhile, if the current SEO project is launched off successfully (with our objective achieved), we will award subsequent projects (our subsidiaries' website designs and SEOs). It will be a LONG-TERM COOPERATION with our company as we understand that the factors affecting top rankings will be consistently changing (algorithm updating) hence the SEO of our website needs to be maintained permanently instead of a month's time frame only. The pay we are willing to offer will depend on your experience, credentials (freelancer or company, portfolio etc) as well as the value-added services you can provide us. Kindly bid for this project (long-term) if you are interested to work with us. *The budget provided over this listing is based on MONTHLY RATE and is negotiable. Thanks.