I currently save everything onto my external hard drive. I'm not sure if the the lightroom catalog itself is saved there but all of my raw files and such are. So when I want to work on a collection I have to have the external drive plugged in. I recently bought a Mac Book Pro and I want to be able to work on my files without having the external hard drive plugged in. Is there a way to do that?
I would suggest you to have a look at the following video link, it should be helpful:How to edit photos in Lightroom using an external drive | Adobe Photoshop Lightroom CC tutorials
Yes with Smart Previews.
Google "Lightroom Smart Previews" and it should turn of many links to articles and tutorials explaining how you do that.