Democrats...are more likely to favor nuclear non-proliferation

Strongly disagree. Both parties verbally oppose nuclear proliferation, but Republicans are willing to go to war to stop it (the last President Bush reasonably thought Iraq was developing nuclear weapons) whereas Democrats are not. (Clinton let North Korea get nuclear weapons and Obama has been unwilling to attack Iran's nuclear program.)

Which party is better comes down to if you most fear a WWI (where everyone acting tough caused war) or WWII (where the failure of the good guys to act tough caused war) type failure.