How many men did David send to visit Nabal at sheep shearing time?

David sent 10 men. He must have been expecting some gift from Nabal for protecting Nabal and his servants.

Source:

1^st Samuel 25:5

Who did the Jews send to ask John the Baptist about his ministry?

They sent Priests and Levites to ask John. Also at least some of them were of the sect of the Pharisees.

Source:

John 1:19, 24

In the Bible, who is the first person God sends out?

Adam is the first person God would send. But this is not for a good reason. God sent him out of the Garden of Eden for eating the fruit of the tree of knowledge of Good and Evil.

Source:

Genesis 3:23

Who sent the wise men to Bethlehem to look for Jesus?

King Herod (The Great) sent them after they came to Jerusalem seeking Jesus.

Source:

Matthew 2:8