If you remove an ad (or any other item) you will be able to view all the related data in Google Ads still. Update the status filter to 'all' and you will see the data for all live, paused and deleted items. There is also the option to filter for 'removed' ads under the status filter.
More info from Google here: https://support.google.com/searchads/answer/3481923?hl=en
Re-adding the keywords in the previous campaign will also have no impact on their performance. When re-adding a removed keywords, Google will reattribute the metrics of the removed keyword to the new keyword.