My next question is, why are you printing this in such a inherently weak orientation? Lay that sucker flat. That plate will be prone to easily snap in half if you put any pressure on it.

I'm Assuming those are bolt holes. Bolts create a compression force. If the layers are parallel the bolt shaft, the possibility of delamination under that compression exists. If the layers are perpendicular to the shaft. there's little chance of that hole failing.

As to the support questions, any time you have material starting to be laid hanging out in the middle of the air, you're gonna need supports.

EDIT: Ignore those first two parts. I went back and looked at your original pics again, and I see why it's not laying flat. I only saw the single plate in your last two pics. But yeah, again, it looks like your supports just aren't working right. Make sure you print supports on anything that over hangs.