No, the question "which day is it today?" is grammatically correct and is asking for the current day of the week.
No, it is more correct to say, "What day is it today?"
Yes, "starting from today" is correct. It indicates that something is beginning on the current day.
Yes, it is correct to write "Please reply by today" to indicate that you are requesting a response by the end of the day.
Yes, by the end of today is correct. It's not a complete sentence, though.
Yes, that sentence is correct. It indicates that there is a possibility of you receiving something on the current day.
No, it is more correct to say, "What day is it today?"
It is this day, today,,,Saturday; The same day that the question is asking.
Yes, "starting from today" is correct. It indicates that something is beginning on the current day.
Neither, apparently, see related links.
The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.The day after today is tomorrow.
Yes, it is correct to write "Please reply by today" to indicate that you are requesting a response by the end of the day.
Both are correct. They are asking two different things.
Yes, by the end of today is correct. It's not a complete sentence, though.
A question mark is used at the end of a sentence to indicate that it is a question. Do you understand? How are you today? What time is it? Is today the day of the meeting?
A question that has a hinted answer attached to it.. such as: You were at the bar at 2:00 am on the day in question, correct? whereas, you could say: Where were you at 2:00 am on the day in question?
Yes, that sentence is correct. It indicates that there is a possibility of you receiving something on the current day.
A question mark is used at the end of a sentence to indicate that it is a question. Do you understand? How are you today? What time is it? Is today the day of the meeting?