I would disable the coolant flow to the intake manifold. First, you are getting plenty of heat off the exhaust manifold already, too much heat in fact. Second, carb icing is not really an issue with Europas given how warm the engine compartment gets. My crossflow had no issues all the way down to -18C (close to 0F) and it didn't have exhaust heat under the carbs.
Can't help with the return hose. I haven't yet seen a simple, clean-looking solution to that problem.