On the search result page, click "Save Search Query" -> on the pop up window, you can change the name of the query to something that helps you find it later.

 Click "Tools" -> Select "Saved Search" -> Find the search query and -> "Run Query"

Click "Tools" -> Select "Saved Search" -> Find the search query you want to edit -> under "Saved Search Query" colume, click "edit" -> edit the query. You can also edit the name of the search query. Under "Name" colume, click "edit" -> edit the name of the query. 

Sure. Click "Tools" -> Select "Saved Search" -> Find the search query you want to combine -> Under "Action" colume, click "Combine Query" -> In the pop-up window, enter the number of the query with which you want to combine the current query -> Click "Combine" -> A new query that combines the 2 queries will be added to the last row of the table.

 Click "Tools" -> Select "Saved Search" -> Find the search query -> click "Delete Query"