Who was the first Muslim missionary in West Africa, where did Prophet Muhammad receive his first revelation, at what age, and who delivered it?

Here are the answers to your questions:

1. The first Muslim missionary often associated with the active spread of Islam in West Africa, particularly through the Almoravid movement, was Abdullah ibn Yasin.

   $$\boxed{\text{Abdullah ibn Yasin}}$$

2. Prophet Muhammad received his first revelation in the Cave of Hira.

   $$\boxed{\text{Cave of Hira}}$$

3. Prophet Muhammad was said to receive the revelation at the age of 40 years old.

   $$\boxed{\text{40 years old}}$$

4. The Angel Gabriel (Jibril in Arabic) visited Prophet Muhammad and delivered the revelation to him.

   $$\boxed{\text{Angel Gabriel}}$$