Feature for better product handling

I have product with different product options and I would like to have different stock amount for every value.

I have for example t-shirt with four different sizes and I would like to use product options menu for customer to choose right size. If there's only few shirts left for that size it will notice the customer about that. I know I can do this by making new product for every size but it would be much easier and classy to do it like this =)

And another idea...

It would be great to have two different alarm limits in stock. When product amount is under first limit it will tell customer that there's only few products left in the stock. And when product amount hits to 0 it will tell that we are run out of product.

And if there's already way to do these... please let me know =)

Thanks,
- Jony -