As long as rain isn't being pushed up from the ground, no chance it's going to enter the building.
No, an awning does not offer the same level of protection.
In particular, installing drainage is pretty much nonsense as it doesn't catch airborn water droplets unless you install a filter which will reduce fan efficiency.
I've never heard of such issues when the 90deg turn is used (it depends on how fast you suck in BTW).
The exhaust fan was blowing out, not sucking in. Even with the fan off, regular rain would not get in unless the storm was severe and catastrophic.