You shouldn't ! Part of their natural cycle is to hibernate during the winter months ! Why deprive a tortoise of it's natural behaviour ?
Yes, it is considered a grassland tortoise. No, it is a desert tortoise. Actually, it can be found in either - it is both.
At around 80 degrees. It is best to get your tortoise a basking (heat) lamp so that one side is warmer than the other.
Being a breeder for 5 years of both Russians and Greek tortoises, I would advise against it. They fight and that responds in injuries and sometimes death.
Either it's trying to show dominance, or it's trying to mate. if there your pets then you should make sure you do not house 2 males together.