PHP Developer - Ongoing/Long Term Project

My company has a need for a PHP, MySQL developer starting ASAP. We're an online furniture retailer based in the US. We just launched a newly branded responsive website based on Bootstrap and need to add a lot of new features to the website. We use PHP, MySQL, MS SQL Server, JQuery, AJAX, Bootstrap, Angular JS. We use an MVC pattern which makes coding very streamlined. We're very open to using new technologies and just started using AWS with their Aurora database connecting with Lambda to send email with simple mail service. We want to develop a long term relationship with someone who will get to know our setup and can work for us at least 20 hours a month for many years. Full time (40 hours each week) would be our preference as we have plenty of work. More than 3 years experience in PHP. The budgeted amount on this listing assumes full time (40 hours/week) for a year. We were not sure how to list this. We're expecting a monthly rate of $500 for 160 hours each month, so it basically comes out to $3.25 per hour. If you can work less, then time can be pro-rated. 40 hours is not mandatory. To get started, we can start a smaller project to make sure we're on the same page.