Was the Messenger, may Allah bless him and grant him peace, a legislator or a conveyor of legislation? And is the Sunnah from the Messenger or is it by revelation and command from Allah?

Naming the Prophet, peace and blessings be upon him, a "Lawgiver" means that he manifests the Sharia revealed to him by Allah, and this is true. However, the technical meaning of legislation (tashri') is exclusive to Allah alone. The Sunnah of the Prophet, peace and blessings be upon him, is a revelation from Allah, brought down by Gabriel to him, but it is not recited like the Qur'an. The Prophet, peace and blessings be upon him, may exercise ijtihad (independent reasoning) in matters where no revelation has been sent to him. If Allah approves this ijtihad, it becomes revelation; if He does not approve it, then the truth lies in the revealed revelation.