Yes, you can take a flash drive and copy the entire Aloha folder from one terminal and put it on the terminal with the older version of Aloha. The only thing you'll really want to watch out for is that some dealers used to like to but the cfg file for Aloha in the Aloha folder as well, in which case there is a chance you might over write it.
I like to grab the whole when possible because reduce likelihood of anything weird happening if that new terminal somehow tried to make it self master when it when it came up, etc... that's rare, but if you get the whole folder, it's going to use all current info from the system it's going to be running on.
I've run across a lot of different user names passwords used by dealers, I can't say there is a default, but you can check to see what the other terminals are using to log on with by clicking on START, then log off/shut down. However, if these terminals were setup on the same system/by the same dealer, it would probably be the same logon and password.