For the first question, we need to know the mass. This was probably given to you earlier in the question, try and find the mass of the calorimeter that was used. Until we know the mass, we can't work out much.
I think for the second question you have it perfect..
q=MxCxdeltaT
q=100grams (volume of both reactants, assuming density is like that of water, where 1ml is 1g) x 4.20 x 11
q=4620J = 4.62kJ of heat evolved.
We can see that equimolar reactants reacted, so the amount of moles is simply (conc x vol) = 2 x 0.05 = 0.1 moles
So 0.1 moles evolved 4.6kJ of heat. We need to work out how much heat was evolved
per mole. 4.62kJ/0.1 mol = 46.2kJmol-1
However, we are talking about the system and since the reaction is exothermic (temp rose) it's -46.2kJmol-1