Yes, in proper context the use of the reflexive intensifies the subject.
"went out in the company of your friends" is correct.
The correct spelling of the phrase is "express yourself" (e.g. verbally, artistically).
No, it isn't. Initiative is a noun. We might say, "Building the new bridge is a great initiative." or "I see you took the initiative in introducing yourself to Mr. Smith."
Yes, "on your own" is a correct phrase to use when referring to doing something by yourself without any help or assistance.
The correct phrase is "she is good company." This expression means that she is enjoyable to be around and makes spending time with her pleasant. Saying "she is a good company" is grammatically incorrect in this context.
I believe the proper phrase to use is "Please make yourself available for this urgent meeting."
The correct phrase is "you and Mark." The word "yourself" is a reflexive pronoun and is not appropriate in this context. You would typically use "yourself" when referring back to the subject in a sentence, such as "You should take care of yourself." Thus, "you and Mark" is the proper way to refer to both individuals.
'In the hope that' is the correct phrase.
If you are referring to this sentence, no, it does not resemble a correct phrase AT ALL.
This is not a sentence it is a phrase and as a phrase it is correct.
This is a phrase, not a sentence. It lacks any sort of verb or predicate to qualify it as a sentence.
The Cajun French phrase for "has started" is "a commencé."