Enhanced Shopping Cart for Magento Store

General information for the business: Our client is a window blinds supplier
Kind of development: Customization of existing program
Description of every module: We need an enhancement to the shopping cart on our Magento site to allow the customer to build a custom blind.
Description of requirements/functionality: Functionality required:

Pricing grid is in mm but customer needs a way to add in 'cm' and 'inch' measurements and get a conversion to mm, possibly via a popup box.

Venetian Blinds
- add width / drop / quantity
- choose exact or recess
- choose control side (left / right)
- choose tilt side (left / right)

Vertical Blinds
- add width / drop / quantity
- choose exact or recess
- choose control side (left / right)
- choose stack side (left stack / right stack / centre stack / split draw)
- choose brackets (face fix / top fix)

Woodweave Blinds
- add width / drop / quantity
- choose exact or recess
- choose control side (left / right)

Vision Blinds
- add width / drop / quantity
- choose exact or recess
- choose control side (left / right)

Pleated Blinds
- add width / drop / quantity
- choose exact or recess
- choose control side (left / right)
- choose control style (currently just free hanging)
- choose bottom bar colour (we need to add images or swatches for customer to select, could be popup box)

Roller Blinds
- add width / drop / quantity
- choose exact or recess
- choose control side (cordless / left / right)
- choose shape (we need to add images for customer to select, could be popup box)
- choose braid (we need to add images for customer to select, could be popup box)
- choose pull (we need to add images for customer to select, could be popup box)

Other
- mismeasurement insurance (that adds 10% using radio checkbox)
- extended guarantee (that adds £4.95 using radio checkbox)

We already have some of this basic functionality (i.e. first three options in each section) but need it enhancing to add the customised options.
Extra notes: A site for comparison is http://www.web-blinds.com

Please note that each blind type has a slightly different functionality, e.g. Rollers need the option to add Braids and Pulls whereas the other blind types don't need braid. Verticals can be drawn in different ways and have their controls on either left or right.

We need to be able to easily upload 'shape / bottom bar colour / braid / pull' images as the range changes.

Blinds displayed in the Blackout and Kids Corner sections are a combination of types (e.g. roller, vertical) so will require appropriate functionality.

We need it to look aesthetically appealing and blend nicely with the design we already have. The site we are working on is www.yourblindsdirect.co.uk