- Special:Properties shows you the properties existing in the wiki: special properties (usually only in italics but here additionally in orange to allow better identification), properties with blue links (respective properties were created assigning a datatype and/or providing infos about the property) and properties with red links (no datatype was assigned, thus they will be of type page, and without infos about the property) Note: This special page is kinda broken right now (2012-10-28). I will file a bug for this.
- I guess you can, but I would not recommend to do it. There have been several mails on the mailing list that report some kind of problem resulting from this. So I recommend creating a new property with the desired name and changing all property assignments from the old to the new property. One may consider using the "Replace Text" extension for this or some bot.
- Special:CreateProperty is provided by the "Semantic Forms" extension, so if this one was not installed you cannot use is. However, in case this extension was installed I would recommend using it since it helps you doing so.
- This depends. I am sure that there are cases there you might want to rename a property. However, I would not do this all the time and only after consideration (see above)
- Yes, Special:CreateProperty adds a standardised message: Created page with "This is a property of type ...".