In America we use the older form have gotten rather than have got when using it as a past participle, as in "I have gotten over it." But in constructions such as "I've got a secret," both sides of the pond are in agreement.
It depends on the situation and wording. Not when writing in a formal tone. Example: He got better at playing the piano. He showed improvement in his piano playing.
"She did not have" is the proper grammar.
"Gotten" is generally considered acceptable American English grammar, but in British English, "got" is typically preferred.
"Got to" can be considered informal or colloquial grammar, but it is commonly used in spoken English to mean "have to" or "must." It is important to use proper grammar in formal writing and professional communication, but in casual conversation, "got to" is widely accepted.
It is proper grammar to say, "I bet you".
"Don't it" is not proper grammar. The correct form is "doesn't it".
no, that is definitely not proper grammar.
That is not correct grammar. A better sentence would be "I went to the supermarket and found this item." In the proper sentence, there is an object and better structure.
No, it is not proper grammar. The correct phrasing is "you and I."
What was there is proper grammar.
It is proper grammar.
There are many grammar practice websites that will help people learn proper English grammar. These are necessary since many people have no idea what proper grammar is these days.