All normal... read this: http://diydrones.com/forum/topics/gibberish-in-cli
basically it's the new way to avoid using the switch to select FLY/CLI mode.
just press enter 3 times (and make sure your baud rate is set to 115K
Edit: maybe you also have some issues with your cables... (sorry did not fully read all your post!)
in flight mode (not cli) it should not jump around...
Try rebooting your computer as well... I've seen strange behavior in MP sometimes due to my laptop needing a clean boot.
Thanks Dany !
That explains the garbling (is that a word :)
In regard to the jumping around it all seems fine now. Copter is behaving as expected. I double checked all the cables and everything seems fine but I can't discount a possible short circut somewhere yesterday.