1. Kings and powerful rulers were a standard feature of the ancient world. This king will be appointed not one that inherits. Inheriting a title would be more a feature of the middle ages than Roman times. The Emperor could appoint someone to rule under his authority as he did with Herod the Great. It is also easy to understand that the local people might want someone else. Kind Herod was not ethnically Jewish and not well liked. It is said he was "a man of great barbarity towards all men equally", so people may well have had Herod in mind as they listened to Jesus' story.
2. Because the King needed to confirm his appointment, he needed to leave his financial matters in the hands of others. Jesus as king is not concerned with the money, he is concerned with the treasure of faith and truth. Christ's servant will endeavor to speak God's truth and spread the faith while acting with love.
3. Jesus is warning the disciples that he will be gone for a time, but will return. In the story he indicates that the new King will return to check on what happened with his money. Those who have been diligent, faithful, and fruitful will be rewarded.
4. Just as an earthly King would punish failure and resistance, so God as King will also punish. In one case the punishment is for fruitlessness. The key line may have been Lk 19:21 where he says "I was afraid of you". Fear of the Lord is praised in the Old Testament but not a fear that results in inaction. (See e.g.. Ps. 34:11; Ps. 111:10; Prov. 1:7; Prov. 9:10; Prov. 14:26-27; Prov. 15:33; Prov. 16:6; Prov. 19:23) Paralyzing fear is a lack of trust in God which is a lack of faith. "Fear of the Lord" is more properly a respect for God and his word.
5. Lk 19:26. In this verse Jesus is merely stating how things often go in this world. The poor get poorer and the rich get richer. Americans think they are poor if they cannot do what the average person can do. They cannot conceive of true poverty, of losing what little they have, but this could happen. Few people today are homeless, and fewer starve in prosperous western society, but the warning is that if we are not spiritually fruitful we can loose what favor (grace) from God we have, just as people can loose shelter and even starve.
6. The king's action of killing his enemies is cruel but Jesus' audience would not be surprised that such a thing could happen. We might not want to think of God in this light but to do so is to ignore other passages from scripture. (See "hell" and Rev. 20:7-15.)