Customizations

Hello all,
I am deciding between two shopping carts and my decision is really based on
the possible customizations to the cart as well as reliability.

Basically to start we will need the following customizations done:

Search:
We sell electric scooters and bikes and we would like the option to search
based on a few different variables.
1. Price
2. Speed
3. Brand
4. Motor size
We would just need some type of form that the user could choose these
options from and it would bring up a list of available products under there
choices based on the info in the database.

Coupons:
We would need to give a percentage or flat rate discount on specific
products or categories. We would also like to give discounts on certain
items based on the first item. Like if they buy scooter1 then offer 30% off
scooter2.

Shipping:
We would need flat rate shipping on each product and the ability to reduce
shipping if the customer buys two or more of a related brand.

Receipts:
We would need to send the customer an html receipt.

Plus we would need more customization down the road.
Please respond with an hourly rate, and maybe a rough estimate of what this
might cost. Or at least let me know if this type of customization is an easy
thing with this particular cart. I'd like to be able to upgrade the cart
relatively easily and I don't want to hard code anything that may effect the
upgrade process.

We also do a lot of traffic over the holidays and I'm wondering if this cart
can handle a large volume of visitors at a time?

Thanks for your help on this I look forward to hearing from you.

-- 
Anthony Minero
President / CFO
http://urbanscooters.com
--