Is there a way to retain the formatting in excel when you paste a table into a post?

Anything pasted would only retain the formatting in the manner used by the editor. So when you paste something from excel, it will not retain it in the same manner you see it in the program itself.

Is there a way to control the default format of the table, i.e. reduce padding?

You can likely adjust it via your theme's CSS but not something by default in the software that you can control.

Thank you gents.