Convert a Template to a Website

I've already created a squarespace site which is basically a creative portfolio showcasing my composition and sound design work. I have 14 projects on there at the moment, and this could be added to or modified as time goes on - linking to videos on my vimeo. I have split my work into featured and commercial, and there is also a simple about page with a small bio and contact details. My intended audience are potential clients or future employers - who are able to check out my work, presented in an elegant, simple fashion that just works with no real bells and whistles. I have hit the limit of my 'developing' capabilities, and desire some functionality that does not exist in my current template. Some coding and tweaking/reworking a few things are required, I don't imagine it to be too much work and hope it is all possible. Below is a simple brief: - Using the Avenue template - Like the design of my current indexes (“Featured”, “Commercials”) - Can have titles underneath, and rollover states… - However clicking on a ‘gallery’ takes you to another page, when ideally it should - just open a full screen lightbox.. - Using a different type of page with a grid gallery inside has the right function, however with no rollover state and no description… Ideal scenario: - Anamorphic grid design (dimensions of current main index) with 2 projects per row - Title of project underneath thumbnail - Rollover state to show that it is a clickable link - either go lighter (or darker might be better) - perhaps also include description of the project to display further information? - Fullscreen lightbox action when clicking on a project Other questions: Is there any way to stop the whole page from loading (refreshing) when clicking on different indexes (featured / commercial)? Can the header stay put and just the thumbnails underneath change? Other notes I am getting a logo / wordmark / favicon designed.