Can we brush our teeth while fasting. Is it permissible?

Yes you can brush teeth while fasting but do not swallow any water or toothpaste

If I have a wet dream during the night in ramadhan, either before or after fajr, and don't do ghusl, is my fast void?

If before fajr did you know and go back to sleep without making ghusl? Did you have intention to make ghusl but overslept?

If after fajr then fast is valid but need to make ghusl in order to pray. Also in order to fast the next day

Will on the day of judgment Muslims be held accountable for wronging a non believer?

Salam. Yes we should not wrong anyone.

I was speaking to a girl over Snapchat and we started flirting. After a couple minutes I felt a discharge from my penis. I don’t know if it was sperm as it wasn’t thick and it won’t a large amount. Does it break my fast?

From your description this is considered pre ejaculation which is a clear liquid. This would not invalidate your fast. However you should turn away from this action and turn towards Allah. When we are fasting it is not only refraining from food and drink but also we fast with our eyes, ears, tongue and limbs by staying away from those things Allah would disapprove of.

May Allah help us all.

Can we say ‘Jesus Christ ‘ as an expression like when we are shocked or like an exclamation? I have some Shia friends who say ‘Jesus Christ’ whenever they are shocked or like an exclamatory expression , is this correct ?

I would refrain from this

I did not understand what Ayotallah means

It means the scholar who has reached the level of ijtihad in his studies. Meaning he can deduce all of the Islamic rulings from their sources.

My doctor has ordered an ultrasound for me, I need to drink water 2 hrs before it and my appointment falls during the month of Ramadan. My results are supposed to go to a specialist doctor. What should I do regarding my fast?

If you are able to reschedule then do so but if you cannot and it cannot not be done without it then follow advice of doctor and repeat fast at a later date.

Is it forbidden to read Quran on a plastic table?

There is no problem with that

My driving instructor my brother referred me is a male and I am female. Is it permissible or not? Shall I try finding a female one?

It would be better to find a female driving instructor

I was looking for narrations regarding the concept of kaffarah for a missed fast during Ramadan. I noticed that all the Shia scholars have consensus on the options and amounts, but I wondered what logic it was based on.

I would highly recommend this book.

https://imam-us.org/wp-content/uploads/2020/12/Islamic-Laws-of-Expiation-Published-by-IMAM.pdf