This is a broad question I realize. But I am unable to get a sense for how difficult it is to use this for page with drop down menus, custom graphics. What I'm trying to do is take some of my sites and redo them as responsive sites. Will I be limited / frustrated in altering styles? My concern is I purchase this and the navigation extension - only to find out it's very difficult to reproduce a site that I've custom designed (such as www.pcmcu.com). Does anyone have general feedback for this concern? I think it's a concern a lot of us may have. I am able to work in code, and am fairly experienced in Dreamweaver.

Hello Tina,
THe Bootstrap 3 Navigation is using a ul>li>a structure, so there shouldn't be an issue for you to style it as you wish, if you have more than basic CSS knowledge.
We do not recommend altering the styles, you should create a separate css style, and include your customizations there.