UTXO question. Bitcoin stuck.

Thank you for those that pointed me to UTXO. This is a follow up post to my first post. I am unable to make satisfactory edits to the first post so decided to create a new one.

Ive attached the progression of the bitcoin movements with stand in figures.

1. I sent .0001 BTC to an exchange from my cold wallet. It sent out 1BTC instead and then gave me back my change of 0.4999
2. Minutes later, at 3:59 I sent 0.1 BTC to the same exchange with my cold wallet. It sent out the 0.1 BTC to my exchange but then it decided to "break apart" the remaining 2 BTC into two: 0.904725 and .995273. This part is confusing to me as I dont know what triggered it. You can see that there is a transaction but no address (the one with ???).
3. At 4:34, I send .905128 to the exchange. I receive it with no problems.
4. I am still waiting for the change 0.995273. I can see it in the address (highlighted in yellow) and it says unspent. Its been two days.

I have only started reading up on UTXO recently. I would really need help.

1. How long does it take to get the change back?
2. Why did it decide to break apart the 1.9 BTC when I successfully sent out 0.1 to the exchange?