Website Optimization, Technical Seo Errors from Audit, and Small Feature implementation

We are seeking a skilled web developer to optimize websites for our small businesses.  Fixing website errors from and SEO Technical Audit,  Feature implementations include: on page call to action buttons, contacts us page, add FAQs to a page, present third party booking software in an iframe, and landing page for ads.  The landing pages would be mocked up with complete text and layout.    The ideal candidate should have experience with Squarespace, Wix, and Wordpress, and have the ability to very efficiently to implement features.  This would be ongoing project across many websites that are clients of our marketing services, we are desiring a long term working relationship.