What is the sign of the entropy change for the heat transfer (enter positive or negative) that takes place?

Sign of entropy change = positive

Oh man I suck at chemistry, but I do know that the sign would depend on which system you are looking at. If you're looking at the system of the first system, it'd be negative, since it's exothermic (giving energy to the other block). The change in enthalpy for the second system, however, would be positive, since it's endothermic (taking energy).

You should be able to use Hess's Law to figure out the equation by setting up your equations to get the reaction you need. The sum of the equation, after products/reactants appearing on both sides, should give you the equation that you need to use to find the change in enthalpy. Then, just determine the pathway you used, adding up the enthalpies (not forgetting negative enthalpies for equations you reversed).

I realize that this is probably already done with, but hopefully that helped. :/
Also, I got like a C+ (B- maybe if the curving is friendly!) in the class, so... :P
But I'm positive on the endo/exothermic thing.