I need a modified / extended version of WP Quiz plugin built for my websites

General information for the website: Need to extended the functionality of WP Quiz plugin to create a different Quiz type

Description of requirements/features: We have WP Quiz (https://wordpress.org/plugins/wp-quiz/) on our WordPress site. The plugin currently offers 3 quiz types with fixed scoring methodologies. We need to get the functionality extended to create a new quiz style.

Features required:

* Our quizzes will have variable number of steps, typically 15-20 questions

* Each question will have a banner image, some text, a slider that users can move with their mouse / right & left arrow keys, and navigation buttons to the next / previous question

* Attached image shows what a sample question will look like.

*At the end of the quiz the results will be scored based on the replies as follows:
Not True = 0
Partially True = 3
Mostly True = 6
Completely True = 10

* Scores will be presented as percentages. We should have the ability to mark some questions as unscored

* The score page will show the percentage, along with an image, and some descriptive text and will include an embedded form (we'll supply form embed code)

* The quiz should sit within our site template on a page similar to this one: http://www.accuracast.es/libros-blancos/adquirir-inteligencia-empresarial/

* Ideally the quiz should be within a single-page app, but if needed, each question could be on a new page.

We'd like the functionality bolted onto this existing plugin, but if you have a better option that is stable, doesn't break any of the themes we use and can do all the functionality of WP Quiz and do it better, then we're happy to consider it.

Specific technologies required: plugins, wordpress, quiz

Extra notes:
As it stands, I think there are 3 options:
(a) the plugin you create would be a lone-standing unit and just work independently of WP-Quiz, or
(b) the plugin extension would use some of WP-Quiz's functionality, thereby requiring WP-Quiz to also be installed, or
(c) a whole new plugin would be built as a fork of WP-Quiz's core files, expand on the functionality, and then be deployed as a new plugin altogether.

Please specify which of these routes you'll take, or if you have alternative suggestions, please clarify that with your proposal.