1) For some reason, Subaru tends to route coolant differently than other manufacturers. The top hose is usually the heated coolant coming from the engine and the bottom hose usually goes through the thermostat back to the engine, thus the lower hose should be cooler.
2) Just because there is a blown head gasket does not necessitate either of those things, it can show itself in many different ways, it just depends on the case. You may be low on coolant or even have an improper coolant/water ratio. Have you checked your radiator to see how much coolant there is in it? have you checked your recovery bottle? If it is dry chances are that your radiator is low.
3) That is often a symptom of low coolant. It's just like trying to heat your car in the winter, though. If you let it idle it takes 20 minutes to reach operating temp, but if you drive it, it comes up to temp a lot faster.
4)Basically, a head gasket goes between your cylinder head and your block. Your block has pathways in it for oil, coolant, fuel, air, etc. The gasket keeps these things sealed from each other. When there's a leak in a head gasket, it might cause coolant to flow into the cylinder, or oil into coolant, or coolant into exhaust, depending on how the crack forms. When coolant is not going where it is supposed to, your heads and your block can warp, making the problem even worse.
Before you consign it to being a blown head gasket, check the following:
Is there a lot of condensation in your exhaust?
Check your dipstick, is there a mayonnaise-y substance on it? or on your oil cap?
Is your air filter wet?
Is your coolant recovery bottle low? is your radiator low?
Also, flathead engines are easier to work on for head-related jobs simply because they're less complicated than other types.