Is there an easier way to make a wall and floor collection than in game? I have 75 walls to make a collection with and I really don't want to click over 75 times to make it in game.

Alas, no. Collection Creator can only do objects, and I know there's a SimPE plugin floating around on the internet that can do clothing too, but nobody seems to have cracked walls and floors. The easiest way I know of is to make your collection then move it to the front of all your collections so that you don't have to go clicking through all your other collectionns to add new things to it.