Russian is the only language widely spoken here. Several people speak Tatar and Bashkir. Finding an English speaker, outside the city of Chelyabinsk, will be near impossible. Carry a phrasebook and dictionary if you don't speak Russian. It's slowly becoming more common for the younger generation to speak some English, but it's still not common.
Chelyabinsk Oblast is generally safe, however be aware that areas of the region are heavily polluted; take precuation when needed. Generally, tourism hasn't kicked off here, and is something of an of the beaten track destination, mainly due to the fact most of the cities are very industrial and also due to the fact they're still several closed cities in Chelyabinsk Oblast. Be aware that you will not be able to enter these cities (and they're surrounded by high security fences). If you did enter without permission, you would most likely face criminal charges. Petty crime rates are not any higher than surrounding areas, general common sense should apply.