Is it permissible to say "Ya Rasool Allah" (O Messenger of Allah) at the grave of the Prophet, peace and blessings be upon him? Has this been established by an authentic or good hadith? And is it permissible to face his grave and supplicate with raised hands?

There is no harm in a Muslim greeting the Prophet, peace and blessings be upon him, at his grave, because of his saying, peace and blessings be upon him: "There is no one who greets me except that Allah returns my soul to me so that I may return his greeting," and because of his saying: "Whoever sends blessings upon me at my grave, I hear him." As for supplication, do not supplicate facing the grave, but rather after greeting, you should supplicate facing the Qibla, as the Companions used to do, and as Sheikh al-Islam Ibn Taymiyyah mentioned.