Hi there,
You sound like someone who knows what they want, so you should know that I'm the man you want for this job. I've got half a decade of experience making sites just like this one, and I know how to make them sing. My HTML, CSS, and Javascript skills are off the charts, and I'm solid with PHP, MySQL, and Google Maps API too.
Most importantly, I've already done something incredibly similar to what you're doing: [login to view URL] I know exactly what pitfalls someone might run into, and exactly how to avoid them.
Do you already have an admin page put together, or will I need to add one? Also, if you'd like I can throw in some free tweaks to your page styling to make everything slightly tidier looking.
You can see a selected portfolio of my other work at [login to view URL] Please, don't hesitate to get in touch. You'll be glad you did.