Re: Lightsaber hilts: remember that Luke built his green lightsaber with very little training, a book, and old parts (to quote Obadiah Stane, he "built it in a cave! With a box of scraps!"). It's possible that he later found better sources of information and better parts. Remember how he found the datatapes on the Chu'unthor? They may have included better instructions on lightsaber construction. It was an academy ship, after all.
Regarding matching lightsaber colours with Jedi Class, I'm sure it's only a game mechanic from KOTOR (and maybe KOTOR II, I haven't played that one). However, the KOTOR comics seemed to follow that same rule. The 4 Taris Masters who were Consulars had green blades, Lucien Draay, the one Guardian, had a blue blade. Celeste Morne was a Shadow (which I associate with Sentinel), and her blade was yellow (so was Zayne's, but he was indecisive; it might mean that he didn't know whether to be a Guardian or a Consular, so he picked the middle-ground). In KOTOR: War, the Mandalorian Knights had orange blades.
TOR seems to remain consistent with this approach, in that Jedi Consulars get green by default, and Knights get blue. Sentinels are an Advanced class of the Knight, which get two blades (which I think are both blue). That said, most lightsabers can have their crystals modified, and there are numerous colour options. My Sith Warrior has a yellow blade right now, and I just sold off an orange crystal.
Sources before KOTOR didn't really codify who got what lightsaber colors. The closest we saw was in 2002, with Episode II, where they codified that Jedi use mostly green and blue (with Mace's purple exception), and Sith use red. It was around this time that the lore of Sith synthetic crystals and Jedi Ilum crystals came to be. Before that, Jedi had dozens of colors (see Jedi Council: Acts of War), and so did Sith (see Tales of the Jedi: Dark Lords of the Sith, Tales of the Jedi: The Sith War, and Dark Forces II: Jedi Knight).
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