I have two main related questions here.
Question one:
I can see how I can set quantity discounts on a product, but I need to set quantity discounts across categories. What this means, is that when a customer selects multiple products from a specified category, or multiple categories that I have predefined, then the quantity discount is based on the total quantity of those products.
I think I might be missing how to do this. If so, could someone be willing to explain it to me step by step please?

Example:
Available Products:
Category A
product 1 $9.95
product 2 $9.95
Category B
product 3 $9.95
product 4 $9.95
Customer Order (with discount applied):
product 1 (Category A) $7.95
product 4 (Category B) $7.95
2 or more products quantity discount (-$2.00)
Question Two:
Based on the available products above, and the multiple category/product scenario, is there also a way to set a price for a certain number of items across categories?
For instance let's say I want a set price if they order quantity of 3. Can this be done using kitting?
Customer Order:
QTY 2 of Product 1 (Category A)
QTY 1 of Product 4 (Category B)
Total QTY 3
Set price of $19.99
Thanks for reading!
Glen