If you have LR CC then there's no reason to keep LR 5.7 around unless you have a specific need to do so.
Both are 64-bit by the way.
Are there any functional differences between LR 5 and LR CC?
How can I keep it from starting up when I insert a CF or SD Card? I hate to delete, but would like to keep it around.
You should be able to keep both. How to prevent LR from starting when you insert a card depend on your operating system. On the Mac you need to launch Apple's Image Capture application when the card is inserted. On the lower left is a little drop down. Choose "do nothing". Unfortunately you have to do this for each card. I don't think there's a global setting. Worse, since I've updated to 10.10.3 every time I reformat a card Image Capture thinks it's a new card. Still working on a fix for that. If you have Windows I don't know how to do it but I'm sure a quick google will get you the answer.
In LR there is a dialog box to check, which say something to the effect of open when card recognize. I unchecked it on LR 5, but not on LRCC. I will see what happens.
Thank you for all your help and support. I very much appreciated it.