Q2 Spontaneous change means delta G <0
it's been a long time since I've done thermodynamics & I can't remember the definitions but are you saying:
delta H (solution) = delta H (hydration) + delta H (lattice)?
In which case, once u find delta H (solution), plug it in to delta G = delta H - T delta S
where delta H- T delta S < 0 because it's spontaneous
and you know delta H (solution) and T, so you find delta S