It is useful to understand that although from 1940 to 1991 Latvia was a constituent republic of the USSR, the official language is Latvian. However, a significant minority (up to 40% nationwide) is Russian speaking. The majority of ethnic Latvians living in the city, not only those old enough to have attended school during Soviet times, can also speak and understand Russian. However, many prefer to converse in Latvian. English and also German are widely understood at places regularly visited by tourists and foreigners but you may be out of luck when leaving the city centre or visiting places off the beaten track.
Public transport in Jelgava is made convenient for everyone. Commuting to Riga is easier than ever. Owing to well developed train system and buses network you can get anywhere at any time.
Buses from Riga 45-60min 2.30 EUR Goes several times in hour
Train leaves almost every hour, so it is the most easiest way to get there.
Electric train line from Riga is just 50min away 2.05EUR (Jul/2014)
A8 highway connects to Riga. 40-60 min ride from Riga Centre.
It's possible to do tandem or solo skydives at Jelgava airfield.
More information at Latvian FreeFly Peppers website 
"Brainstorm", probably the most popular rock-band from Eastern Europe, has emerged from a cradle called Jelgavas 1. vidusskola (Secondary School No 1), where also such National talents as A. Skrastins, A. Vaznis, E. Radzina, A. Skele, E. Repse have made their first steps in the world of fame.
Latvijas Lauksaimniecibas Universitāte — University of Agriculture of Latvia is a well recognized university.
Melno Cepurisu Balerija - rock music bar, mexican food, kebabs, fastfood, good latvian beer
There is few clubs/pubs.
Most popular are Jelgavas Četri Balti Krekli — club where play Latvian music
Tonuss — club, with several halls. Place with a lot of young people.