Exar Kun being a Sith using a blue lightsaber is very similar to how Anakin after falling to the dark side in Episode 3 used his blue lightsaber to destroy the Jedi Darth Maul lightsaber was inspired in Exar Kun lightsaber so there is a possibility that Lucas took the character of Ulic Qel Droma as a base or inspiration for Anakin Skywalker in the Prequels
The same here. A few other characters and plot points taken from, or maybe based on, the early EU as well.