A lot of new info, images, names, etc. have recently been reveal through a “visual story guide” type book for Rogue One.

http://www.starwarsnewsnet.com/2016/05/new-images-with-characters-vehicles-and-descriptions-from-rogue-one.html

Here are the character names extracted by JediBibliothek from the images:
Felicity Jones plays Jyn Erso, a gifted soldier and warrior.
Diego Luna plays Captain Cassian Andor, an officer in the Rebel Alliance
Jiang Wen plays Baze, a freelance assassin*
Alan Tudyk plays the CGI figure K-250, a Vollstreckerdroide and evidently an imperial model, but teams up with the rebels.
Riz Ahmed plays Bodhi, a rebel soldier.
Pao, an alien who is described as “fierce warrior”.
Donnie Yen plays Chirrut, a spiritual warrior.
Bistan, another alien who is described as “fierce warrior”.
Ben Mendelssohn as director Krennic, the military director of the Empire, to defend the Galactic Empire against the theft of Mission rebels.

There’s also a new Rebel starfighter introduced in the film, which is kind of surprising.
It’s apparently called a U-Wing;.

And there’s also a new imperial fighter called TIE-Striker;

Two of the members of the main cast will apparently be aliens;

And there’s a new type of storm trooper called “Death Troopers”;