Because God has ordained the ends as well as the means. Our preaching to them is just as ordained as their belief in it. If they are appointed to eternal life they will believe, as Acts says.
Here is what Calvin said about the Eucharist:
He emphasizes the reality that the Eucharist, as a sign, points to, which is the crucifixion of Jesus Christ applied to the believer.
The Reformed believe that Christ died to save you and that He gives you the sacrament as a sign of what He has already accomplished. We don't believe Christ died to give you a sacrament that may or may not save you.
Biblically, Elders and Bishops refer to the same office. There is no priest other than Jesus Christ.
You are making a choice, you are choosing to sin. If you do choose God, it is because the Holy Spirit has granted it to you. Romans 9 answers this very question:
A lot of people don't like this passage, but it is sinful and unfaithful to censure it. Instead, we should pray for the faith to accept it.
You quoted Scorpion and I both, and I'd like to see his take as well.
Predestination is a kill-shot for any works-based system, so no one is going to emphasize it other than people who are really big on Faith and Grace. We do not set God's moral imperatives He gives us against the higher theological truths that He reveals to us. We do not have a legalistic understanding of His commandments as it was in the days of the Old Testament. Rather, God has regenerated us, justified us, and empowered us to walk in the ways that please Him.