The Search Library browser (which is the default one) lets you enter search terms and play all matching songs. It also supports complex searches. Finally, it lets you limit the number of results; right-click on the text bar and select Limit Results. To display your whole library, don’t enter any search terms.
The browser remembers the last eight searches you made automatically. If you want to save more, you can right-click on the text entry and select Edit Saved Values…, which will let you name and save searches permanently. Saved searches will appear above automatically remembered ones in the menu.