They will work, as long as you get the appropriate bottom bracket.
The weight difference is nominal. They're only slightly heavier than, for instance, a pair of sugino 75 cranks (which are what 90% of the fg you'll see are built with).
The 1/2 cm difference probably won't be noticeable unless you dig into turns at higher speed. Not familiar with that frame though, so i'm not sure if it'd be an issue; depends on the position of the bottombracket shell.
Keep in mind that you'll be limited to using bmx chainrings (sprockets), so you're going to have a ceiling of roughly 42t when looking at quality sprockets unless you get the profile (i think they make it) adapter, which will allow you to use 110bcd rings but will add even more weight.

ED: yeah, it's profile who makes the adapter.