1 - you should be able to reduce the yellow tint by reducing the redsky decay color saturation in the tweaks tab of the atmosphere node.
2 - your water seems smooth because your camera is much higher above the water compared to the second image - I guess.
Lastly: personally, I find the first render much more beautiful that the second one. Why go for it then?
Forgot to tell you that in my example render, I have also increased the enviro light strength on surface to 2m and chanced the surface color of the "background node" to 0.018, which helps with GI somewhat and brightens up the otherwise black sky. It's also important that you use relatively high GI quality and GI sample details to something like 2/2, but if render ime doesn't play a big role, 2/4. This should give you much more details from the global illumination (enviro light).
Frank
