1. Why did Nevada swing R considering it's similar to Arizona? Is it only because of the high % of working class?
Yes, mostly. Plus there are some good numbers of rural (outstate of Vegas and to a certain extent Reno areas) that happen to be really responsive to populist politicians. So the kind that may not have turned out for Sandoval, Angle, Hardy, Heck, etc.
2. Why did Colorado also voted more R compared to 2012? High hispanic population like other western states + the most college educated state in the region. It just doesn't make sense to me.
Mostly just the national swing. It's still clearly going hard toward the Democrats. Maybe just not as fast as say Virginia or Texas on the other side are.
But very few states moved left in terms of raw (percentage) margin in 2016.
Gary Johnson and perhaps also McMullin may have ate into the support from certain Obama voters who chose that third-party candidate over Clinton (Colorado's unique in that small-L libertarians almost certainly draw more from the D's than the R's regularly)
It's also right across a border from Johnson's home state/governing place of New Mexico, what with its ski resorts as well. Just think Colorado Springs: marijuana legalization, low taxes, gay-straight alliances, wealthy white and blue-collar, anti-inverventionist dovish, it's a libertarian's paradise.