I am not sure of what other worth you are referring to. I only know that my prayers do not change God's mind, since I do not have power to compel or convince God. I see Him as being above that.
What does the communication consist of?
Usually, improvised prayer from the heart. I like to think that I have the type of relationship with God such that I can tell Him anything, so I do.
Do you not participate in prayer chains? Do you not ask God to do this, to help you with that, or to alleviate the other?
Sure I do, all the time. But this is no waste of time. These prayers themselves were just as ordained as the thing sought for being granted, or not. I don't know what God's plan is going to be on a given future matter, so I should pray about everything. The Bible says to. The Bible says that prayer is efficacious, and it is, since it is all part of the process of God's plan being implemented. God changed my heart to want to follow Him. The Bible says that to follow Him is to pray, so I want to pray.
Give us this day our daily bread: a little asking - now what use is that?
It reminds us of our dependence on Him ahead of anyone or anything else.
And forgive us our trespasses, as we forgive those who trespass against us - a promise to do, to act, and further asking Him to grant us something - of what use is that?
Again, it is a reminder to us what He does for us, and what He wants us to do.
And lead us not into temptation, but deliver us from evil. - more asking. This is not communication only, this is worship and asking Him to help us. I don’t believe that this sits very comfortably with Calvin’s beliefs.
Why in the world would Calvin have any problem with worship and asking God for things? It's all through the Bible. God wants us to worship and ask Him for things. We believe that all prayer pleasing to God GLORIFIES God. It is our purpose, as you said so well earlier. Therefore, it is useful regardless of the fact that we are not changing God's mind.
If they are ordained, then how are they ordained? What would happen if you forsook all prayers from this moment forward? Would you still attain Heaven? Would your place in Heaven be diminished?
The Calvinistic approach really doesn’t make sense to me since prayer consists of such things as asking for God’s help, and since nothing that we do matters, then what does asking for God’s help accomplish?
If prayer is for our benefit only and has no relation to God and His actions, and it is a reminder to us only of what He does for us, then why ask Him for things, why not simply use prayer as worship. It makes no sense.