Pop Ups and product creation

I have a few questions.

1. I am looking for a way (possibly one with no monthly fee) that allows a pop up when a specific product is added to cart. For example, if you selling items such as bags, when a bag is added to the cart, a pop up appears and asks if you would like to customize it, if yes, leads you to page to add the customizations, if you do not want to customize, gives you option to continue to cart or continue shopping.
2. If you are using Bopo product bundles, is there a way to create a product bundle but then if they would like to add additional items, they can add one at a time? If not with bopo, is there a way. For example, there is a product bundle with 5 charms, but if they would like to add additional charms, they can click, add charm to bundle, add another and so on.
3. Lastly, is there a way if one adds an item to cart, they have the option to swop part of it, for example, if they add a bag to the cart, they can opt to swop their strap from a range of straps?