Tkinter vs Python
If I want to use tkinter, do I have to select that as the language at the start or can I use python as a language and import tkinter. And if I do have to use tkinter as a language at the start, can I just program in python for everything else with the addition of tkinter?
You can do either. You can either import it, or make a tkinter repl. I would suggest going with making a tkinter repl, instead of importing it though.
tkinter is just python with a few displays setup so you can actually get things to output on to the screen.
Because of this, you could literally code python in tkinter, but it would be a waste because of the extra commands used to setup an x11 display.