Some Advanced Actions on Add to Cart and Checkout

Hello,
My team and I, are doing a pretty big customization to a MarketPress installation.

Currently I have to do two things.

1st. Everytime I add a product to cart, I need to attach a custom info, even if I add to cart two products of the same one. What means qty will be 2, but I need specific data for each one.

2nd. I need to perform some action when user finish the checkout, generate some files that I don't want to generate it until the checkout is finished to save some server resources.

I know this needs some custom code, but my question is if there is someway to do this without modifing MarketPress code, so I can update everytime MarketPress is updated.
From what I see in the code, the answer is no, but I'm hopeful.

Thanks for your help!