Outlook 2013's Contacts have a new default view called People and new Contact Cards. I think the People view is confusing and contact cards make using contacts more complicated. They are definitely not my favorite new features, and based on the number of questions I receive, the People view and Contact cards are a source of confusion for many users.
"I cannot change the contact photo while editing."
The contact photo can't be changed from the Contact card. Switch to the View ribbon and apply a different view. Open the familiar contact form to access the Picture button on the Home ribbon, Options chunk. (Or double click on the photo to select a new one.)
You can also open the contact form from the new Contact card, if it has links under View Source. When the card is in Edit mode, the entries under View source are not clickable - click Cancel to exit Edit mode.
"I cannot find the attachment I just added to a contact."
The new contact cards don't display the attachments. To access attachments added to contacts you'll need to switch to another view and locate the contact or click the link under View Source to open the contact form.