Should hard drives be encrypted prior to an operating system installation?

When employing full disk encryption, should hard drives be encrypted prior or post the installation of an operating system?

If the former, is this supported by operating systems such as Microsoft Windows and Linux?

Does this or can this improve the security of the device? If yes, how?

Is there a particular method of encryption that should be considered?

Moving a file between two drives on one SSD – will it be copied?

When moving a file within one drive, the file is not copied-and-deleted. The table that refers to the files is just updated. And as far as I know, that is not the case on 2 drives on an HDD. But SSDs are different, there is no physical space dedicated to each drive. (source)

So my question is what happens when a file is moved from one drive to another on the same SSD, are the bytes copied and the original deleted, or is some table updated, thereby thrashing the SSD less?

There’s already a duplicate question here. But both answers claim:

each partition will have it’s own physical area of the drive to itself

and

Partitioning a hard drive actually designates physical regions for each partition. [and in a comment:] SSD is still a hard drive, it just doesn’t have a disk.

As far as I know that’s wrong. See here.

So will someone who knows more about SSDs please tell me if they are correct in their assessment despite their mistake?

Slack startup pauses on disconnected network drives on mac

On macOS 10.12.6, I have a network drive added as a Login Item so that it’s available when I’m on the same network as the drive. It’s also in my Favorites in Finder. If I’m not on the same network as the drive, it’s inaccessible, that’s fine.

What’s strange is that if I start Slack when this drive isn’t available, it will wait for a long time and then I’ll see an error from Finder about the drive not being accessible. I think I have to dismiss the modal twice before Slack finally finishes loading all the way.

Is Slack trying to enumerate all my folders/drives and access them on startup? Is there a way to disable this?