Used Car Sale Site

I would like to create a site to compete with this website:

http://www.autotrader.co.za/

A popular South African, used car sale site. I would like to mimic the functionality of this site. So to list but a few things, the site must have:

A buying section of the website which will consist of:

A “Search used cars:” search box, with make and model, year, price, mileage etc.

A “Browse used cars by make:” box as seen on the bottom of the autotrader site.

As well as an advanced search page as seen here:
http://search.autotrader.co.za/www/cars_search?doSearch=N

A “Selling” section of the website whereby users can upload pictures, videos and a detailed text description of the car that they wish to sell, distinguishing between private users and dealerships.

They should be able to place an advertisement online by choosing various different packages.

Example, Package one: 2 weeks, R100; 4 weeks, R150, etc. And it should be able to accept payment via credit card or EFT. As seen here: http://www.autotrader.co.za/includes/channels/cars/sell/select-product.jsp

I would also like a finance calculator as seen here:
http://www.dealer.co.za/financecalculator_new.html

I would also like a seperate section for 4x4s and Bikes.

I would also require some sort of admin panel to make changes to all of the above and keep track of all of car advertisements etc. I would also need to be able to modify the different categories that cars can be submitted to, as well as the filtering categories on the advanced search. So that if I would like to add additional categories at a later stage it is possible for me to do it myself.

I realize that it is a large undertaking and the programmer will need to be willing to work closely with me over IM and VOIP applications so that we can achieve the end product that I have in mind.

Looking forward to your cooperation,
Linden