>Is there a way for time &/or date to appear on the >Control Panel (top LCD)?
No, but why would you want that? If you really need to check the date/time you can press the Playback button after you shoot an image and see the timestamp on the LCD.
>Does anyone have feedback on using an eyeFi SD memory card?
They're handy, but not very fast. The write speed to the card itself is acceptable, but the file transfer over WiFi is painful - especially with RAW files. They're probably aimed more at the point'n'shoot community and people shooting smaller JPG images which would transfer faster.
Depending on the application you need this for, it could handy if you need to remote mount a camera on time lapse and transfer one image at a time.
If you're going out shooting for the day in JPG Fine / RAW and want to come home, set the camera down and let it transfer, that could be painful.