You can use this utility to split the file into more manageable sizes, so they will fit on the floppys
http://www.freebyte.com/hjsplit/
You could also use a Parrellel port cable, called a null modem cable, to do a DCC (Direct Cable Connection) from one computer to the next. Then you could exchange the files much easier, the draw back is that this way will cost you some money. If you want to use this cable route, you can then use this programs called File Maven to trasnfer the files, http://www.briggsoft.com/fmdos.htm
If you dont want to spent much money, then just go with the file splitter above. Both programs are FREE.
A benefit to the DCC route would be; with some understanding and work, you could share an internet connection with another computer.
As far as which Juno to use, I can't help you there, never used their service.