I made two separate bookings.

Booking 1 (flight in May):
Miles cost : 49500
Cash cost : $76.10
Details : Booked using the app without trouble. Miles deducted immediately. eTicket email received about 1 hour after booking. Cash charge appears on my credit card and is no longer pending.

Booking 2 (flight in August):
Miles cost : 49500
Cash cost : $45.40
Details : Tried to book on the app but an error occurred. Tried again on the website but still got an error. Called the number that came up, used the Cart ID to have the agent make the booking for me. Miles were not deducted and ticket status was "processing". Cash charge was in pending state. After ~48 hours of waiting, I used the chat feature on the website to speak to an agent. The United agent pushed the ticket through and I received an eTicket email. Miles are still not deducted. Cash charge remains pending.

Overall status :
On the United website, I can see both bookings under "My Trips".
Booking 1's ticket status appears as "ticketed at (insert date and time)". I am able to scroll down to select "Email receipt" and successfully receive an email with an eTicket number.
Booking 2's ticket status also appears as "ticketed at (insert date and time)". I am also able to scroll down to select "Email receipt" and successfully receive an email with an eTicket number.
My United account shows that I still have 49500 points remaining.

Questions:
Am I just somehow not charged the miles for Booking 2? Some kind of system error when the phone agent pushed my reservation through?
What happens if I log in right now to change both bookings to different flights that cost additional miles? 49500 miles is enough to change both Bookings to more desirable routes.
If I use up the remaining 49500 miles on a completely different booking (Booking 3), meaning I will have 0 miles remaining on my account when I check in for Booking 2, will they realize the error and try to charge miles but since I don't have any, somehow cancel my ticket? That would be highly unfortunate.