According to the Bible, God instructed Moses to use genocide, not slavery.
Depends on the instance. On close examination, genocide only applied to peoples whose lineage could be traced back to the Nephilim – an interesting pattern, especially with the link to the Goliath story.
Yep.
I am reminded of the Chinese wisdom for dealing with conquerors, knowing it will not be long before the advantages of their culture will soon turn these conquerors into more Chinese.
At that point in their history the culture and traditions of Israel were too weak. We saw what happened even when Solomon took many wives from different cultures – soon the religious practices from those cultures had spread among the Israelites. So I can see a reason why God might have taken a different approach at that time.
The point is that morality is not absolute, unconditional, and unchanging. The circumstances do make a difference.