Having problems installing new range hood in my parents old house

(Disclaimer: Please excuse any dirt/grime in the pictures. As I said, this is an old house that hasn't been maintainenced in forever)

I was able to remove the old range hood with relative ease, although getting that ground wire un-twisted from the old ground screw on the hood was a little bit of a pain. But when I want to install the new hood, which has the same dimensions as the old, the flap on the new hood wouldn't fit into the old cutout in the wall(this is a 'through wall" installation'

As in, this: http://ift.tt/1ndh0Cc

Wouldn't fit into this: http://ift.tt/1UuXXAL

So now I'm kinda stuck and don't know what to do... I also had another question. The old range hood had a cutout in the back where the house wires would go through and into kind of a junction box area underneath the hood so you could connect the house wires to the hood wires. This new hood does not have that feature. The wires are just sticking out of the top of the hood like this: http://ift.tt/1ndh0Ce

Will I be okay just twisting the hood wires and the house wires together, capping them with wire caps, and putting electrical tape on them? Would that be safe? I thought the ground wire from the house needed to be twisted around a (usually green) ground screw on the range hood itself?

Thank you for any and all help with these two problems. I'm a little out of my element here.

Submitted March 01, 2016 at 04:06AM by mrfunbun http://ift.tt/1UuXXAJ