Alastor Moody's magical eye

1. Moody's Magical Eye

In GoF, there are numerous instances in which we see what Moody's magical eye is capable of doing. Barty Crouch Jr., disguised as Moody, was able to see through solid wood, and Harry's invisibility cloak, which is supposed to be impenetrable. Also, if i recall correctly, didn't he see through Harry's robes and compliment his socks during the Yule Ball? So, if Moody's eye can see through all these things, does that mean that, to Moody, everyone looked like they weren't wearing any clothes? That's a really weird thought that has been bothering me for a long time, and I really want to know the answer. Another somewhat related question I had was, how did both the normal eye and the magical eye work at the same time? For us, both eyes function at the same time, but since for him, each eye had a different function, I was wondering how that would work.

2. Owls and Tracking

In OotP, Harry sent an owl to Ron and Hermione while they were at OotP headquarters. Despite the building being protected by the Fidelius Charm, Hedwig was able to reach Ron and Hermione without any trouble. Even in other instances, letters that were sent by owl post effortlessly reached their destination, without the sender having any idea of where the receiver was. From this, I've come to the conclusion that owls can track anyone, anywhere. So why couldn't the Death Eaters in Book 7 simply have sent letters to the people they were looking for, and then set some kind of tracking spell on the owls? Or even simpler: they could've just grabbed broomsticks and followed the owls. This probably wouldn't have worked if the destination of a letter was protected by the Fidelius Charm, but they still could've caught a fair number of people using this method. So why didn't they? Why did they have to resort to less effective measures like Snatchers and the Voldemort taboo?

Bonus question: do any of you have a random side character that you hyperfixate on for no reason at all and come up with a ton of headcanons for in your head? Mine would probably be Oliver Wood; I don't know why, but I've cooked up a whole backstory for him.

I would really appreciate it if someone knew the answers for these questions!

I have some questions I want to be answered, so if you know the answers pls comment them. Ty

1. How did Dumbledore and Moody see through Harry's cloak? According to Xenophilius Lovegood, “We are talking about a cloak that really and truly renders the wearer completely invisible, and endures eternally, giving constant and impenetrable concealment, no matter what spells are cast at it." Harry was supposed to be completely invisible, how did anyone see through it?

2. Why did no one else hear the basilisk in the walls? I know Harry was a Parselmouth, but by that logic, everyone else should've been able to hear a snake hissing in the walls. For example, everyone heard the snake in the Dueling Club, and I would bet money that the Basilisk was way louder than a random snake. Parseltongue only lets you translate snake hisses. Everyone else should've been able to hear the snake hisses, as just that, snake hisses.

#HPinfluence