Yes, especially if you're trying to be polite to someone you want to hurry up.
The second one is more correct.
Yes. The form who is the nominative, as opposed to whom.
yes it is a real word. It is also correct grammatically and more stupid is not correct.
It may be grammatically correct, but it is a logical absurdity. more/fewer is about counting more/less is about amount … so… no, it is not correct.
"More greater" is not grammatically correct because "greater" already implies a comparison, so adding "more" is redundant. Similarly, "much more greater" is also incorrect because "much" and "more" are both comparative terms. It would be more appropriate to simply use "greater" or "much greater" to convey the desired comparison in a grammatically correct manner.
I am, you are, he/she/it is, we are, they are.
The phrase "how don't I" is not grammatically correct. A more correct way to phrase it would be "why don't I."
No.
No, "most friendly" is not grammatically correct. The correct form would be "friendliest" when comparing three or more things.
Yes
The second one is more correct.
Yes, "is much more easily" is grammatically correct because it follows the correct order of adverbs (much, more, easily) when comparing multiple items or degrees in a sentence.
Yes, the phrase 'what they're doing' is grammatically correct. For example: What they're doing is wrong.
No, it is not. The "question word," why, should be at the beginning of the sentence. Why was she promoted?
Both "you and he" and "he and you" are grammatically correct, but "you and he" is more commonly used in English.
No. Us is the objective case, not the nominative case (we). It should be: We teens need more sleep. Or: We, as teens, need more sleep than others.
Both are grammatically correct, but "do not feel" is better usage than "are not feeling."