Select an object in details view to add to gridview

I have a page with a drop down to filter reults from a text box query, that returns results to a details view:

The results are displayed in a pageable details view like this:

Yet once again I am confused in which direction to go to get the functionality I want.

I want the end user to be able to select an item from the details views above, or multiple items. Even be able to do subsequent querys and select more items that would be "compiled" into a "list" that could populate a grid view when they were fininshed selecting their items. Then they could print the gridview.

Let me know if the approach I am thinking of would work or if there is an easier way.

I would have a check box in the details view. Then through code first I would create an entity data object that would be the "list". I would use the selecting of the checkbox as the event to insert the item into the data object.  The grid view would display the data object and then I would use java script with a helper print method, to print the gridview.

As you can tell I am tall on the concept and short on the details. I think I could stumble through this. Is there an easier way?  Are there pitfalls I should watchout for? Is there a certain direction I should head?

Also with the data object would I have a bunch of "orphaned" tables of data out there after the end user left my site? Would I need a way to perge them after their session was over?

Thanks in advance.