Quickie: Would Trump be a disaster?

No.

That's the simple answer. No.

Trump would be like Rob Ford. Trump would be able to do some things, but would be reigned in from doing the more crazy things. Trump would have some support in Congress (and if he wins the election, it's likely the GOP will have control over both houses) but that support will not stick with him if he tries to do some of the more radical proposals on his agenda.

Most importantly, however, and what differentiates Trump from Rob Ford, is that Trump says whatever the heck he feels like. I have no doubt that Trump's "Muslim Ban" will end up looking a lot more like "A ban of muslims from entering the country if they've spent X amount of time in any of Y countries" and that his "Wall" with mexico will amount to "An upgrade to the existing fencing along the Mexican border"

Put simply; you can't base what a Trump presidency will be based on what he says he will do. You can only base it on what he's actually done, and been willing to do, and based on that, he will not stand out as 'the only crazy' in the list of Presidents should be win.