How do I get more product coupon code options than the ones that come built in?

I need to be able to create different types of coupons than just a % or absolute price reduction. Specifically I need to be able to create a coupon that creates a new price regardless of what the old one was, or at least be able to exclude some products from being affected by the coupon (manually or products that are for sale).

Example from http://connectandtrade.com/frank-worth :
The default price for all photos are $189. We offer one photo each week at $29, and want to also give out coupon codes that lowers the default price to $59. If we do that by reducing the absolute price by $150 people can get 5 of the $29 photos for free (I tried). If the coupon reduces the price by 80% we get less than $6 for the $29 photo.

I would also like:
1. to give discounts connected to quantity: If you buy 4 you get them for $59 each.
2. a coupon for free shipping (preferably be able to control domestic vs international)
3. a coupon generator so I can give a lot of people a personal coupon that only works once

I really hope you can help or else I'm in big trouble

Best,
Knud