I'm not sure. Do you think of the "Mark" button in the search dialog (CTRL-F)?
`Search->More->Mark All` of ctrl+shift+m by default
No switching between editor window and search window.
Same
Simply select the desired word by double clicking or using Shift-ArrowKey.
And you don't even have to select the word, the one the cursor is in is used.
Did you try the feature in the add-ons plugin?