God sent Ananias to Paul rather than revealing directly because not only did Ananias relay the message, but he was also able to welcome Paul into the Christian community. This also meant that the Christian community was informed of the change in Paul's life, and was ready to welcome him, as they might not have been had they not had this foreknowledge.
Ananias argued with God because, knowing Paul's reputation, he was fearful.
It takes courage to obey because we so often do not believe that God knows best, and we prefer to use our own judgement. It is a step into the unknown in faith, and that is frightening.
Ananias laid hands on him - the Christian act of blessing and transference of the Holy Spirit. He prayed with him and explains that he is the emissary of Christ, and does not come in his own strength. In welcoming him to the Christian fellowship, he explains what will happen - that he will regain his sight, and be filled with the Holy Spirit.
Yes, I have felt these promptings. Sometimes, like Ananias, I have not had the courage. But when I have overcome this, I have discovered that the blessing falls not only on the person to whom I ministered, but on myself as well.