Take a look at this thread: Attachment and media gallery upload restrictions
Before you can upload media you need to have made a certain number of posts in the forums (an anti-spam measure). If you take part in the forums for a little longer you should be able to upload media.
Another question, though, if you don't mind. I notice many photos have a "date taken" feature, though I'm having trouble finding that option when I upload :S
That's not something you can set yourself.
The EXIF data is taken directly from the image file - and is only present if your camera stores that information in the JPG file and the file hasn't been manipulated by external software which strips that data.