It’s no problem to use a Wacom stylus to draw selections, and yes, you’ll probably find that with a stylus it’s easier to control precise drawing with tools such as the Lasso selection tool, and when painting masks with the Brush tool, compared to using a mouse or trackpad. Photoshop has worked with Wacom tablets for around 30 years.
As for the display, it depends on your specific needs. I don’t know enough about the Wacom tablets with displays because I use a simpler Wacom Intuos tablet with no display, but as far as the display itself:
What kind of artwork do you usually create?
How do you usually need to deliver your art? Print (on press), web, video…?
How tight are the color accuracy requirements for delivering your art?
Will your art require delivery in HDR?
That will help you get answers based on what the color specs of your display should be.