gallery in template or plug-in?

I am super new to wordpress, so please be patient with me. I am planning to use a thirdparty theme through themeforest, Gallery function is paramount for me. Is it important that I find a theme that comes close to meeting my needs or do most people find plug-ins that offer the function they need? Here is what I need my gallery function to do.
*preview of select images but password protected for full search and viewing
*function as a subpage (exp work>images>abstract
*sortable by tags (exp; red, abstract, original)
I need the gallery to be easy to add to and upkeep. Ideally I would also like clients tobe able to create their own “lightbox” or project folder where they can save images and email them to me for quotes.