CyrodillWarrior The crashes may be caused by Mods, but the only way to know for sure is to test in a vanilla game. You can move The Sims 2 Legacy folder from Documents\EA Games\ to your desktop and launch the game, which will generate a fresh save folder for you to test in. If Mods are the issue, you can do a 50/50 test to narrow down the problematic Mods.
As for essential mods, Mod the Sims has some threads with such lists. Some Mods fix bugs, others fix annoyances, and some add small, quality-of-life changes; I recommend you go through the list and see what exactly suits your gameplay.
