We are are planning to migrate MX7 to CF11 and am trying to determine how much effort it will take. In the meantime, we are currently using Oracle 10.2 but am getting pressure to migrate to Oracle 12C before we migrate to CF11. Is this possible?
This all depends on the code. You might find no code needs touching and it all works fine, you may find large parts need rewriting.
Some code will have been depreciated since CF7 and wont work in CF11. Your best bet would be to install CF11 trial / dev edition and see what breaks. There is a feature in CF 11 Administrator called Code Analyzer that will check your code and tell you where there are problems. Its not perfect but will give you a good idea of the obvious changes that need to be done.
Oracle 12C is only supported with CF11. You will have problems getting it working with CF7.