Instagram account disabled but only on my iPhone?

Every time I try to sign into my Instagram account on my iPhone it says that my account was disabled, however I can sign in on laptops, iPads, and other peoples' phones. What is the cause of his? My account was not deleted, I'm just unable to sign in from my phone. In the picture, the top got cut off, but it says "your account has been disabled for violating our terms http://…" and I did not even violate any terms. Can someone please help?

Is it cheaper to get a new iPhone on a plan or buy it unlocked and add a cheap plan?

I can either buy the phone for $250 and pay a monthly $80 plan with data for 2 years or purchase the unlocked phone $800 and pay $30 - $50 a month - I might not get data but it wouldn't be a big deal to me, I'm just trying to find a deal thats not ridiculously expensive cause I can't really afford too too much right now. Which would be better?

How to unlink an apple ID from an IPhone?

I just bought an iphone from my friends that has been factory reseted, but somehow the phone is still linked to another account. Is there anyway i can log out from my computer?

To the people who lost their iPhones?

When you got your new iphone, does all the things you have on your old phone go to your new one or is it all the data lost? Ty c:

Added (1). Btw does all your messages stay too or are they deleted?