No real choice, just responsibility

Unfortunately, that there's no real choice this election, just your duty towards the world.

Can the President launch at a whim?

Actually, yes. Deterrence only works if you can guarantee to use nuclear weapons at any time. 

Therefore, "the president has basically unconstrained authority to use nuclear weapons, a seemingly insane system that flows pretty logically from America’s strategic doctrine on nuclear weapons. The US needs a system to launch weapons fast for deterrence to work properly, which means one person needs to be able to order the use of nukes basically unencumbered. The president is the only possible choice.
This entire system, however, is built around a basic faith in democracy: that the American people will elect a sober, stable leader who understands the seriousness of nuclear weapons."

http://www.vox.com/2016/8/3/12367996/donald-trump-nuclear-codes

Never off the table

Trump seems to think nuclear weapons can actually be used in contexts beyond deterrence.

https://www.youtube.com/watch?v=jCHQPCXbt1w

Trump wants to be unpredictable with respect to the use of nuclear weapons

https://www.youtube.com/watch?v=QVTAaJ1fzfc

and

https://www.youtube.com/watch?v=VSnVb4i_ZZ4

Imagine ICBM's would be detected under Trump

How would Russian officers respond to his unpredictability?

Apologies for the post. Just ignore if you don't care about nukes.