Replacing Impeller and other cooling componets

[mariner150]

I have a 1989 150HP Mariner Magnum II Model #7150453ND.

I replaced the impeller.

Are the rubber fins supposed bent a certain way when the impeller is installed in the housing?

I noticed part of a rubber hose near the starboard side of the lower unit near the seal at the oil passage. The rest of the hose is missing. Is there supposed a hosed attached and going some where? What is it?

I do not think the thermostats and poppett valve have ever been replaced. How do I know when to replace them?

Thanks