"Node Picker" for custom module? I'm building a custom module so the editors at my company can select several nodes and spit them out as a newsletter. There are some modules that get me halfway, but due to some specific requirements, coupled with me really wanting to wrap my head around creating custom modules, I'm starting from scratch.

I understand the hooks, and have set up the menu, permissions, and most of the form fields where users can select a template and other options. I'm stuck at the part where they actually pick the nodes.

I was thinking I can probably create a View with some exposed filters and maybe hook into that, if it's possible. Ideally, I'd let them drag and drop the nodes, reorder them, etc.

I'm not looking for someone to code this out for me, would just like to be pointed in the right direction.
Without knowing the full scope or what modules/custom code you've already developed, this could be done fairly easily with a hook_menu, custom form and a content type. The new content type would have a multi-select (probably auto complete) node reference field which will allow for simple reordering. You could then implement a hook_menu with a custom form returning all the newsletters in a select list and when the form is submitted you can use node_load() to get all the referenced nodes from the selected node. Your submit handler would pass the applicable values to whatever batch mail module/functions you're using.