Ordered a new computer online, will arrive Monday

[LPBBEAR]

11. Yes

Isn't it possible to just copy and paste the entire folders on to the USB flash drive?

Sorry, didn't see your post until this morning.

Yes, Thunderbird works the same way as Firefox. This is what makes the 2 applications easier to deal with when transfering from one system to another compared to Outlook for instance. No time consuming export/import process. Just copy/paste.
Copy the entire folders for Thunderbird just like you did for Firefox from all 3 original locations on your old system and put them in the same folders in your new system.
Make sure you don't open Thunderbird on the new system until you've done this. If you have already opened Thunderbird before doing this delete the auto created folders on the new system, copy the old folders, and then open Thunderbird. It should automatically see all of your old data at that point.

Let me know how it goes.