Mind the 40 day Gap of the Resurrection

Jesus was crucified, buried in a rock cut tomb and rose from the dead on the third day. So who saw him and when did they see him? Who were the witnesses and how did they record what they had seen, heard and experienced? Jesus was on the earth for 40 days before the New Testament says that he returned to heaven. So exactly what did he do for 40 days? Where did he go and who did he speak to? What was the reason for hanging about on earth for so long instead of enjoying the glories of heaven? If it was so important for Jesus to do what he did for 40 days why doesn't the church have more to say about this resurrection ministry? Just what is this 40 day gap all about?