CS-Cart site - need to make product filters SEO friendly

Project Description:
I have had a custom web store (selling shoes) built using the cs-cart backbone. CS-cart builds SEO friendly URLS for products and categories. CS-cart also has a filter addon which allows the customer to filter the products. The SEO friendly URLS and filtering are both active, but filtering does not produce SEO friendly URLS. Specifically:

My test site is http://www.colorfulcreationsshoes.com/
My Womens Shoes Category is: http://www.colorfulcreationsshoes.com/womens/
If someone wanted to view just size 6M shoes in this category, the URL is: http://www.colorfulcreationsshoes.com/womens/?subcats=Y&features_hash=V47.
If someone wanted to view size 6M shoes in Gold, the URL is: http://www.colorfulcreationsshoes.com/womens/?subcats=Y&features_hash=V47.V35.

As you can see, when the .html file is built, every filter is setup as a different URL. Consequently, every possible filter combination is treated as a completely different URL by Google even though 80% of the content is identical between pages.

I want someone to rewrite the code so that filtering is SEO friendly. Specifically, I don't want filtering to dilute the page rank of the page/category being filtered. This can be done by changing the filtering to a Java function, by making all filtered URLs cannonical, etc. I personally don't care how it is done, I will pick the method that will most effectively preserve the page's rank and that does not substantially increase the page load speed.

As part of this project, I have a second SEO friendly URL fix I need done. Currently, there is an addon that builds the SEO friendly URLS for categories and products. There are a few different options for building the URL, but for products, the only currently available option is to build the product page url ending in .html. I would like the product page URLS to end with "/" rather than ".html". This fix should only take about 5 minutes as it involves finding one variable and changing it.

99% of the project work is in fixing the filtering.

When you bid, please explain how you are going to fix the filtering issue, and why that is the best solution. I will award the project based on that explanation.