The photos technically go into Photos app so the only edit you can do is the Enhance button. I'd suppose you could use another app like the Photoshop iOS app to do edits.
The best thing to do is set the in-camera jpeg processing (Picture Style) to something you are happy with because that is what is sent to the iPad.
I was doing a form of this last weekend while in NYC.
Basically, I transferred my JPEG images from my SD card to my iPad, edited them using iPhoto for iOS (increase saturation, contrast, sharpening), then uploaded them to a Journal to share with friends on the web. It worked great!https://www.icloud.com/journal/#4;CAEQARoQrO-zbxiQQA0jkR0a_0IsSw;BD839AA6-F65E-4FDA-B68A-D6CFE050DDB4
Disclosure: The above images were shot with my S95, not my 5DMarkIII, but the point of my post is workflow, not camera type.
I have an Eye Fi card, but wasn't using it. You should know that many people have reported an Err80 (power error) when using the EyeFi card with the 5D Mark III, me included. It is a result of the power going off on the camera but not the card. It is easily fixable by removing the battery from the camera. However, I have decided to avoid the issue entirely and simply use a regular SD card and the camera connection kit to get the photos onto the iPad.
If you need to show off your shots on the iPad even faster, I agree with the above person who said to use the in-camera processing via the Picture Styles. Move those over to the iPad with the Eye Fi card is probably the fastest way to show off semi-processed images.