I have a normal iMac, with most of my documents stored on a WD 1TB Hardrive (It has roughly 800GB left). If I downloaded OSX Lion and chose the install location as my ext. hardrive would it have any effect on how the computer works and how it sees that there are files on my hardrive?
Also, if I then decided to boot from my Mac again (So that would be Snow Leopard, right?) would the computer function normally again? and all the Lion files (assuming they were compatible) be able to function with Snow Leopard?