Was Uncle Frank a jerk to everyone else too?

Not really, but who knows? He did call them 'moi petite enfants' affectionately in this movie, but he was being a dick since he ignored his sister-in-law who said that the shrimps were for later.

Nope he was only ever being a jerk too Kevin in both movies

And remember this.... "You'd better not wreck my trip you little sourpuss, your dad's paying good money for it"

He's a *beep* cheapskate!

Yes.

Yep. He played the role well.

Honestly, I don't even know why the dad would invite him on vacations or family gatherings; or put up with him to start with. Uncle Frank was a cheapskate and a moocher, his wife was totally complicit, his kids were retarded and one of them always wet the bed, and he was an absolute douche to everyone, particularly Kevin.

But then again, Mr. McCallister wasn't known for being very intelligent. Hell, he didn't have much of a personality to start with, much less know how to be a real dad and keep track of all of his kids. He usually just footed the bill and let his wife do everything. He's sadly what's known as a "cookie-cutter parent," in the realm of tv story-telling.