On the mirrors,
I personally dont like how high and close these electric 90-91 mirrors are. For me they feel like they are blocking some of the view. I think the manual ones are personally better plus you have more mirror to look at at.
On the vents,
the vents will help keep the engine bay cooler and keep the engine from overheating. This is nothing new, I did them on my Cherokee and there is not even enough room for a mouse under a Cherokee hood. After I did that I could sit in traffic or on the trail with he A/C on and never overheat and that's in the Arizona summer. A cooler engine is a happier engine.
They are designed to be riveted in but I will be painting the hood and the vents and the rivets are powdercoated white to match the vents so I will use SS hardware instead.