Since you are talking about opening files, I assume you experience these issues in Files.
I solved the issue of “Single click and double click leading to the same result” by going in “Preference”, then “General” section, change “Single Click” to “Double Click” for “Action to Open Items”.
Then you can achieve the behavior you describe:
- Single click selects the file
- Double click opens the file
To open the menu, I use the Menu key from the terminal keyboard layout (I don’t remember where I have found this solution on the forum).
In phosh, long press already open then menu (which stays).