How to get & use applications on external SSD
Hello all:
I have a VisionTek, 1 TB, SSD external drive with Thunderbolt 3 port (APFS formatted).
-- I want to use it as both a bootable and backup drive for my 2017, 27-inch iMac with fusion drive.
-- In an emergency if my iMac hard drive isn't working, I want to be able to boot up from the SSD AND use my applications (e.g. Adobe Cloud apps like InDesign, Microsoft Office, Dropbox, etc) directly from the external SSD.
-- I already have MacOS Mojave installed on the external, but noting else.
How do I get my applications on to the external drive so that I can actually use them there?
1) Do I have to download them again and install them from scratch onto the external?
2) Do I use Time Machine?
3) Do I use Migration Assistant?
4) Do I use software like Carbon Copy Clone?
What are the implications of each of these since I already have Mojave installed on the external? Will I have to erase the external and stat over doing something, I'm not sure what?
What is the step-by-step procedure?
And what happens down the road when I need to backup my iMac to my external? Would I be backing up my applications OR reinstalling them if there are updates to the Apple and non-Apple apps? If there are updates, would I have to reinstall/update on both my iMac and external?
I don't understand the meaning of terms the terms: copying, cloning, migrating, moving, restoring or whatever term one uses to be able to use an application on my external. I've read numerous articles in the Apple knowledge base, but find them confusing.
I’m not understanding the distinctions and implications. I feel totally lost.
Thank you.
iMac 27″ 5K, macOS 10.14