In the book it talks about Luca having a place where he and his crew gambled all night long. Also when describing Luca's day to day it say something alone the lines of he sleeps till afternoon, has breakfast, makes his rounds to collect, spends time with a whore or two, and then either goes to a club or goes to his crews hangout a gambles all night.

If the don had any idea an attempt was going to be made on his life, he would have never sent Luca, cause like all of you have said, before you can make a move on the don you have to kill Luca. Vito didnt realize he was playing right into his enemies hand.