Yes, as the protasis ( if-clause) of an unreal condition.
yes, it is
The phrase "you look suspect," is grammatically correct. It contains a subject of you, the verb to look, and suspect as the direct object.
The grammatically correct phrase is "the same as hers".
This phrase is not grammatically correct. One may say, "regardless of ... " or "whether or not ... "
Yes, although somewhat archaic. "Instead" is a shortening of this phrase.
Yes, 'for free', is grammatically correct.
The phrase "how don't I" is not grammatically correct. A more correct way to phrase it would be "why don't I."
The phrase "You are not knowing" is not grammatically correct. Instead, you can use "You do not know" or "You are not aware."
Yes
The phrase "Is you don't miss me do you" is not grammatically correct. It should be rephrased to something like "Don't you miss me?" to be correct.
The phrase "had already left" is grammatically correct. The phrase "had already been gone" is not grammatically correct.
yes, it is
No, it is not grammatically correct to say "keep stick to." The correct phrase would be "keep sticking to" or "stick to."
Yes. It is a noun phrase.
The correct phrase is "that was you," as the verb "was" agrees with the singular subject "you."
Yes, it is grammatically correct. "Part and parcel" is a phrase that originated as a legal term in the fifteenth century. It means an essential or integral part.
Yes, the phrase "I came home at about one o'clock" is grammatically correct. It follows a subject-verb-object structure and conveys a clear message about the time of arrival.