I am a Scenic/Set Designer and was wondering if there was a library that I can save a drawing of a 2x4 to so I can insert/add it to a drawing as many times as I want without redrawing it?
You have always been able to link (remotely references data) or append (import from other file) data from any other Blender file into the current one by going to File > Link or File > Append.
You can do this for most data like models, groups, materials, lighting and animation.
In recent versions asset management got considerably improved by making the file browser able to display Blender image thumbnails even for Blender internal data, and making Blender able to generate per data-block thumbnails.
Just go to File > Data Previews > Batch-Generate Previews and make sure your file browser is set to display thumbnails.
In a way, Yes, you can Either use File>>Link OR File>>Append.
You have to manage your own library structure through the file system though, and when you do this, you want to make certain that you group your objects in a group with a descriptive name. The group maintains a lot of things (including keyframe and material information - So there are pros and cons to this, so you have to manage these assets understanding that things like this also come along for the ride).
That way after you select one of the Link/Append functions, you browse to your desired asset blend file, and then you get presented with the internals of that file. Now all you have to do is double-click the Group folder, and pick your named group.