You can't equip a "wrong weapon". All classes can only equip the appropriate weapons, and pretty much every weapon has a use. Especially in PVE. --- Rest in Peace City of Heroes: April 27, 2004 - November 30, 2012. We will miss you. Cause of death: "Realignment of Company Focus" by NCsoft.
It takes barely anytime to learn the 5 skills for each of your weapons. Even if you somehow go without using one of your choices until level 80, you just need to fight a few mobs to learn the skills. --- One person can make the world scream Do everything....with passion
Each weapon has 2-5 skills that are quickly unlocked by killing enemies with that weapon (5 skills for two-handed weapons, 3 for main-handed weapons, and 2 for off-handed "weapons"), with some minor exceptions for Thieves (they have a synergy skill based on weapon combination in place of their third main-hand skill) and Elementalists (they have a unique weapon skill set for each attunement).
You also get slots 1 healing skill, 3 utility skills, and 1 elite skill, which can be chosen from a list of all of the skills you've unlocked (of the appropriate type). The three utility slots become available at levels 5, 10, and 20, and the elite slot becomes available at level 30. You unlock the skills themselves by purchasing them in your hero window using skill points. You get 1 skill point per level, and can (and should) earn additional skill points by completing skill challenges that are strewn throughout the world (there are about 200 of them IIRC).