Theme, template, or widget?

I hope this isn’t too vague, but I am trying to determine how to search for a theme that provides a specific functionality without having to preview every theme. Actually, I might be looking for a widget, or a theme that includes the widget(s) that will provide the functionality I’m looking for. Here’s what I’m looking for:

– account creation: any visitor to the site can create an account. They must have a valid email address (for verification) to create an account, and users will create their own passwords. This info needs to be stored for subsequent logins.

– each account will have access to 1-3 pages that are interactive where they will simply “check off” items from a list. Each line item needs a check-box (or similar) that get little check-marks or some other graphic. I would like to have some form of graphical representation indicating the percent of the total complete as each line item is checked, either a circle/pie-chart kind of thing or even just a simple progress bar graphic. This info also must be updated, stored, and re-accessed with subsequent logins.

This is going to be a very simple site – no shopping carts or any e-commerce, no social media links, no SEO, etc. This site will be little more than a homepage where users login or create an account, and then 1-3 pages of line-items that get checked off. It does require a database to store user info.

So, am I looking for themes that include the widgets that provide this functionality, or a widget(s), or a template? Thanks