Hi.., ItsBrandon,
The answer to your first question is as follows:
Nothing created by God is in vain, as in His word.
This means that God created heaven and hell to have contents.
The same analogy as you make something there must be a function. Example: you make a shoe rack, surely it's for storing shoes not for clothes.
Likewise hell, there must be a function, namely for those who do not worship to God who created all humans.
The answer to your second question is as follows:
God who is believed by Muslims is very Compassionate towards His creatures, to the extent that in the Quran many states that Allah Ta'ala is the Most Compassionate and Most Merciful.
All Prophets invite their people to witness and worship only to one God, Allah Ta'ala.
But the attitude of his followers there are those who accept and those who refuse. Allah Ta'ala who had created the universe and its contents wanted all His creatures to admit that their God is only Him.
The analogy is if you have two children, and your two children always do good to everyone, one child acknowledges that you are his father. But your other child doesn't admit that you are his father, how do you feel? while this child is nurtured and raised by you? so is Allah Ta'ala, He created you but you don't admit that Allah Ta'ala is not your God, how?
Moses, Jesus, Muhammad, and all the Prophets acknowledged and only surrendered to Allah Ta'ala Who had created them too, but there are people who followed them and some refused them.
Allah Ta'ala has sent down His books and His messengers. Whoever is obedient then he/she will go to heaven, but for those who deny him, he/she will go to hell.
As a proof that Allah is Most Merciful, He has told through His books and His messengers before humans die. So it's fortunate for those who follow the teachings of His messengers before they die.