Wa Alaykum Assalaam, sister. I remember that hadeeth from high school, but don't have the reference handy. Perhaps another member can verify it.
I know that Muslim reported that `Aa'isha narrated that the prophet, peace be upon him visited the graveyard of Al-Baqee` and said, "Peace be upon you, the home of believing folk. What you've been promised has come to you and you are kept on hold for tomorrow and we shall, God willing, join you." So, what would that mean if they couldn't hear him?
Also, Bukhaari and Muslim reported that Qataada narrated from Anas who said that the prophet said, "Verily, when a worshiper is laid in his grave and as his companions leave, he hears the clicking of their shoes..."
I found the second one but the first one u mentioned I was not able to. Of course I am searching in english and the names are usually spelled differently.
Sahih Bukhari Volume 2 Number 456
Narrated Anas bin Malik
Allah's Apostle said, "When (Allah's) slave is put in his grave and his companions return and he even hears their footsteps, two angels come to him and make him sit and ask, 'What did you use to say about this man (i.e. Muhammad)?' The faithful believer will say, 'I testify that he is Allah's slave and His Apostle.' Then they will say to him, 'Look at your place in the Hell Fire; Allah has given you a place in Paradise instead of it.' So he will see both his places." (Qatada said, "We were informed that his grave would be made spacious." Then Qatada went back to the narration of Anas who said;: Whereas a hypocrite or a non-believer will be asked, "What did you use to say about this man." He will reply, "I do not know; but I used to say what the people used to say." So they will say to him, "Neither did you know nor did you take the guidance (by reciting the Qur'an)." Then he will be hit with iron hammers once, that he will send such a cry as everything near to him will hear, except Jinns and human beings. (See Hadith No. 422).
As you were saying here is another hadith about making salaam:
Sahih Muslim Number 483
Narrated Buraydah ibn al-Hasib
The Messenger of Allah (peace be upon him) used to teach them when they went out to the graveyard. One of the narrators used to say this in the narration transmitted on the authority of AbuBakr: "Peace be upon the inhabitants of the city (i.e. graveyard)". In the hadith transmitted by Zuhayr (the words are):"Peace be upon you, the inhabitants of the city, among the believers, and Muslims, and God willing we shall join you. I beg of Allah peace for us and for you.
I hope this didn't take away from the original post question.