Adding Meta Information

I’m working on a new plugin and seem to have hit a wall. I’ve seen this done a thousand times, so I know it can be done, I’m just not sure what to search for to find the answer.

So I’ve got an extra field in the post screen. I’d like the information from the field to be submitted with the post. I would also like to add this to the postmeta table, however there’s two problems with that.
1. How do I get the post_id from the newly submitted post?
2. What is the action name for this?

Thanks so much!!