Building an E-commerce site

This job includes creating a site from scratch. We want to sell kitesurfing equipment, courses and complete kitesurfing packages online. As our merchant account is not yet active we want to start straight away using PayPal to collect payments, but the site needs to be compatible with our e-merchant account, and once it's ready to use we will switch to that instead. We also want space for articles and information about our courses for SEO reasons. The person responsible for the site after it's online is good with computers, but not a web designer so it should be easy to add more content and articles after the site is ready. So we are looking for a simple, clean and nice looking design that we can manage by ourselves after the site is launched. It's important that the person who does this job is knowledgeable about SEO so the on-page optimization will be good as we will strive to rank high on google eventually.