Regarding the turbine inlet temperature, I can give you T7, which is the low pressure turbine inlet temp (RB211 is 3 spool, but I guess you know). T7 also known as the EGT on the 757, limits for a RB211-535C:
ground start, in flight start:570°C
max continuous:795°C
maxtakeoff 850°C
max reverse:795°C
max overtemp 870°C
Again, these are limits, actual EGT depends on a lot of factors.
What do you mean by engine Mmo? The aircrafts Mmo is 0.86 (B757-200)