To answer the first question you need to go to the Sporting Code, Section 5 where the definition of a Mondial is: An International Sporting Event comprising of WPC's in all IPC competition disciplines (except IS, CP, SP, WS and Para-Ski, which may be included or excluded at the option of the Organiser) taking place concurrently in the same location. Within that definition the third Mondial is happening in Chicago, USA 11-20 September 2016.
But, in fact, it will be the 4th Mondial.
The concept of a multiple international competition encompassing all the parachuting disciples was the vision of the (then) President of the French Parachute Federation, Bernard Colas. France was accepted as host to the 2nd FAI Canopy Formation World Championships from 20th to 27th August 1988 and was inspired to include the other disciplines practised at that time: Formation Skydiving and Style and Accuracy, and make it a Mondial. At the closing ceremony display Patrice de Gayardon gave the crowd a taste of things to come as he swooped the kayak course.
France remained loyal to this vision and in 2003 hosted the 2nd Mondial in Gap which included all the current IPC Parachuting disciplines (except Para-Ski). The United Arab Emirates at Skydive Dubai were the hosts for the 3rd Mondial in 2012 and even managed to include a Para-Ski competition utilising the indoor Ski slope (although not an FCE).
When you read the definition above it is obvious that the original simplicity of the concept of a Mondial is no longer possible as so many of our disciplines now demand "special" conditions (Wind Tunnel, pond, large object free landing areas, snow) making it difficult for one organiser to cover all disciplines.
In Chicago, there are 6 World Championships taking place, as the organiser, Skydive Chicago, took up the option to include Speed Skydiving, along with Freefall Style & Accuracy Landings (both senior and junior), Formation Skydiving, Canopy Formations, and Artistic Events, in all 23 gold/silver and bronze medals to be fought for.
In Gap in 2003 the French introduced the Patrice de Gayadon trophy to be awarded to the Nation with the top medal haul at the end of the Mondial. Twice this has been won by France but with 35 Nations from 6 Continental Regions competing who knows what will be the end result from the 4th Mondial.