Questions about Firewall Aliases

[badkuk]

First off, I apologize in advance if I'm posting this on the wrong forum.

I have a few clarifications about aliases:

1. When importing, is it safe to just leave the sid field( cca89844-518c-4a23-b6f9-695814fe9937": {... )  blank?
I've actually tried it and it seems to work fine, I'm just concerned that it may mess something up internally.

2. What does the "Loaded#" field mean?

3. How is this data stored internally? Database or plain text file?

tia