Animals have no eternal soul and therefore they act purely on instinct. They have no true eternal spiritual state. God told us to have dominion over the animals, so yes, they are "less" than us. We must not abuse them, but we may use and eat them.
God is perfect. We must not think of Him as a Care Bear in the sky. God has no limit on His Power, but there are natural limits within the Universe God created that would cause imbalance and destruction if He altered them. God is the most just (ethical) Being in existence. God is all good, but we must understand that He has a perfect balance of love and hate. God is a wrathful God because wrath by itself is not wrong. We can never see the end of God's power as it is infinite.
Correct, we have free will to put our will in God's hands and therefore we have free will to rebel against that.
Yes, Jesus is the only One Who could do the work (die) for us. However, Jesus says to send up treasures to Heaven. After salvation there are treasures of the mind and actions that can be sent to heaven when we do them. We don't do this because we have to, but because we believe it is what Jesus would want us to do.
We have to die. When we die and stand before the Throne of God Jesus will stand in front of Christians and tell the Father that His death covered our sins. God will not punish us because Jesus took our sin away. He paid our fine.
No, the wheat is just a picture. The wheat will be harvested when God decides it is time. Time is relative and God has a plan. The whole world will never be Christian.
When the end comes a process will be kicked off. (You read Revelation) The people on earth who are Christians will be Raptured and given new bodies as will the dead in Christ (removing our sinful nature). Jesus will rule the world for one thousand years as people on the earth continue to live and die. Christians will live with mortals as immortals and Satan will be locked up. Mortals will still sin because they have their sinful nature.
God said the end would come when it is like the days of Noah. The plan God has for the world isn't for us to question, just study, as there is nothing we can do about it except act as Jesus would act. He is our perfect example.
Think about it. Islam says you can fly airplanes into your enemy's buildings, treat women like livestock, and beat them. Only certain people Allah likes get into Heaven and you have to work to win his favor. Does that sound like Christianity? God judges the heart and you and I will agree that those are terrible things to do. It is best for us to leave judgement up to God, but never assume anyone is going to Heaven if they aren't following God's laws for salvation (accepting Jesus' gift of Salvation).