Here is another touristic promotional film(longer) if you are interested to learn about the host country and what you might be interested to visit during free time: https://youtu.be/SAsDOgjIYNg
Majority of participants of the conference would not need visa to visit Armenia. Some who need visa can easily obtain it at the airport upon arrival. However there are a few countries, citizens of which may need to apply for the visa. Please, check out the requirements at the web site of Ministry of Foreign Affairs of Armenia.
The weather is very mild in September, warm and dry. For details and statistics check here.
Food and Nightlife
An abundant breakfast is served practically in all Yerevan hotels, and it is usually included in the price. Lunch will be served at the Marriott hotel, venue of the conference.