The basic tutorial on the linked page should work as written. Things the LC does not do:
Has fewer pins
Does not have the hardware for the audio library or OctoWS2811 mulit LED drive and some of the timer related libraries
Less current capacity from the onboard regulator
3.3V only for IO pins
None of these impact following the ordinary tutorials or using it as a custom keyboard.
One thing to be aware of if working from non Teensy tutorials is that the classic Arduino Uno defaults pins to input on power on where the LC has them disabled for lower power consumption. So libraries/examples written for for Uno may need pinMode(INPUT) added for the relevant pins to work. Using the Teensy libraries you are likely to use for a keyboard https://www.pjrc.com/teensy/td_libs_Bounce.html
Are already setup correctly.
Note, the tutorial listed was written in the time when Teensy 2.0/2.0++ were introduced. The LED pin that they mention for blinking the LED is now pin 13 (same on the Teensy 3.2, 3.5, 3.6, and 4.0).
In terms of tutorial 2, the card that came with your Teensy lists which pins support PWM. In the case of the Teensy LC, pins 3, 4, 6, 9, 10, 16, 20, 22, and 23 support PWM.
In terms of tutorial 4 (and other places that I've missed), the Teensy LC runs at 3.3v, not 5v like the Teensy 2.0/2.0++ did. If you feed in 5v to the LC it may damage it. But in the case of tutorial 4, just change 5.0 volt to 3.3v when it is showing connecting to the power rail.