Storage, Apple TV, and movies

Hello all,

My mac's start up disc is full. I would like to free up space and have done several measures to do so. I found that most of my storage is from movies that I have either purchased off of my apple tv (itunes) or bought and plugged in the digital code to be able to access through my apple tv 4th gen. I've noticed the movies that I purchased through itunes have the cloud icon with the arrow pointing down next to it. The ones that I plugged in the code do not; however, I'm assuming they are both in the cloud because I can reach them all from my phone and ipad.

1. If I delete these from my mac, will I be able to still get them directly through my apple tv from the cloud, or is this a final detete?

2. If not, am I able to hook up an external drive to the apple tv and still reach the movies with the apple tv remote?

I know I can do it through my mac, but that would be a pain to do every time I want to watch a movie

3. If not, how does somebody build a itunes library on their apple tv? I was under the impression that I could one day have dozens and dozens of my own movies on apple tv, and I am currently having trouble with 5. I'm having trouble finding out how/where to store these movies for easy watch and efficient storage.

I'm starting to think that we had it fine with the blurays, lol

Thank you in advance for your help!