Mega Menu with Walker Class & CSS Design Implimentation

I’m in early stages of site development for a Public Figure / Personal Blog for a film producer director and writer.

I do not want time wasters or opportunists. I will only respond to people who have read the brief below in detail and understand the requirements and scope.

I also need a ball park PRICE. An estimate on time and how much before I proceed.

Objective
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To create a mega-menu to my specific design that smoothly animates down and uses the Walker class to display the most recent videos, and posts (e.g. a category list in horizontal format, date ascending) with their respective preview thumbnail Picture, Title and (Possibly Excerpt on hover) within the drop down.


CSS Design
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I've designed each and every drop down (attached JPG files). These can be modified slightly to incorporate edits as we go along but give a visual idea of what I need.

Mega-menu Walker Type 1 - VIDEO/POSTS WITIH DESCRIPTION
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When creating the menu in the admin area, it would have an option to display a category list (up to 5 videos depending on screen width) horizontally with the category_description in the first column.

Each post type would display:
- Video/Post Title
- Thumbnail Preview,
- Link to Post Entry
- Excerpt on hover (tooltip)
No meta data required such as author etc.

The Link of the Video/Post beneath the Thumbnail Picture would take you to the actual Post Entry page.

Videos would be differentiated from Posts with overlay play button. (e.g. Post type = video).

OPTIONAL : It would be SUPER cool (but not essential if too complex) to play the video by launching a model light box. This could be indicated in an extra icon on the Preview Thumbnail.

Mega-menu Walker Type 2 - VIDEO/POSTS WITH SUB-MENU TABS
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On the Newsroom menu I plan to display a list of sub-categories as tabs that when you hover over display the Posts and their Thumbnail, Title etc. within that category within a horizontal row. All Links would go to the Post Entry and no light box needed.

Mega-menu Type 3 - WIDGET or JUST PLAIN HTML
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The mega-menu would not ALL be Walker class. There will be some other functionality like Contact or widget usage. Plus a Social Link dropdown which would be a single column but on hover change colour to each social brand colour. Please refer to designs.

All the above would also have to work on mobile devices so some CSS Design tweaks would be required there too, although I’d like to rely on existing plugin CSS (if that is used to create this).

Current set up
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Site uses Enfold theme and just some basic plugins.

Choice - Either:

1) Utilise current theme’s (Enfold) existing mega-menu functionality, and add on tailored walker class functionality
or
2) Add a plugin with Walker PHP functionality such as http://menu.megamain.com
or
3) Tailor own plugin or php

I would supply PSD file originals and examples on how to animate them (very basic just slide down).

I also want this to last. I don't want it to fall apart after an update, so please bear that in mind.