My first lip filler question about the corners of my mouth!!

Concern -> My mouth is a bit saggy and
 my upper lip
 seems thin and small, so
 I wish I could give it some volume naturally and make it look longer horizontally!

I'm planning to get my tail and filler done, but
 I have some questions!

1. What is the difference between domestic/imported?? What are the pros and cons?
 2. I heard there are side effects... are they common? Why do side effects occur?
3. How much does domestic/import usually cost?? Roughly average (each part)
 4. How long does it usually last?
5. Will it be resolved when the time comes? Do I have to melt it when it comes loose??
They say it just melts away, but is there any need for aftercare?? Something like removal
 6. So it's periodic?!
7. I have to smile often, but when I smile, can my shape change, my smile become less noticeable, or
 the corners of my mouth not go up? Because your smile should be pretty!
8. Does it hurt a lot??
9. Please recommend a hospital!
⭐️I am a 19-year-old student, so please be as patient as possible with brokers.