Air gap intake and heater hoses

I somewhat agree with that but I'm going to use the factory hose holder behind the alternator to keep everything still. Brass will last forever... I have brass frost plugs too.
The factory used steel because it's cheaper.

That'll work great. One thing, however: I do not like using brass. Sometimes due the softness of the material, brass cracks due to vibration. That fitting is susceptible to a lot of engine movement, and vibration. I'd use steel for better strength, or better yet stainless steel for the anti-corrosion factor too. (Note that the OEM fittings at the engine were steel).