How do you forum posters explain that evil exists despite God being, all powerful, all knowing and all love?
Evil exists because of sin: when created beings (angels or men) decide to disobey the moral law of God, and the consequence is that evil permeates all things. Sin is far-reaching, and is the reason there is a lake of fire judgment coming. The Bible says that God will judge everyone according to their deeds.
Why does God permit or create evil?
God let created beings go their own way (rather than cling to the holy nature of God), in order to show that we cannot live up to God's holy nature without God's help, which requires faith in Him. And in order to show that forsaking God's help has bad consequences. We are in a spiritual war/struggle, in which we must do mental and spiritual battle against the ways of sin. The Bible says that God is a mighty warrior, and we are required to believe for His help in winning those battles to the end. We get God's help through trusting in Christ.
Or did God not want it for anything?
God has no needs, but He desires that the whole world would know Him. The Bible says that one day the whole world will be filled with the knowledge of God, and it also says we are created for His glory and pleasure, and that by His side are eternal pleasures. Therefore, we are put in this world to seek Him out, according to Apostle Paul's teaching in Acts 17.
But if you mean "Did God not want evil in the world?" - No, God does not WANT evil in the world; but the Bible says that God wants everyone to be saved and come to the knowledge of the truth. But in fact, many angels followed Satan into choosing evil; that is, using their will for wrong reasoning, and this also happened to every human being who ever lived, except for Christ alone. Jesus called Satan the father of lies, and every person is born under the control of Satan's lies. The way out of that is to know the truth that is in Jesus Christ. So what God wants of people is clearly stated, to repent (from sin) and believe the gospel (that Jesus saves us from sin).
No, it's as real as a heart attack.
Why did Jesus create the situation of the crucifixion and go through that?
He said that no one takes His life, but He lays it down on His own accord. It means that He displayed the ultimate love to lay His life down for the redemption of all men, in the worst possible conditions. The event also shows us that love shines the most when good deeds are done in the worst of situations.
Why does the victory of death and Satan, take so long to fully establish?
The Bible says that God wants to bring many sons to glory, which requires lots of time for population growth. Furthermore, it takes lots of time for people to mature spiritually, and develop the permanent godly character they need, which is happening in every generation. Part of the Christian life is living by faith that Christ will raise us up to immortality, even though we don't see it happening right now. Faith is the basis of a vital relationship with God.
Will the fallen angels and souls ever repent?
Fallen angels can't repent, this is why the lake of fire was created, for the devil and his messengers (including all people who refuse to repent and believe the gospel).
But what do you mean by "and souls"? Are you talking about souls of mankind? If so, then it is possible for any human being to repent and believe the gospel, and many are. But we also know from what the Bible says, and what missionaries tell us, that the majority of people are on the road to hell. Jesus said, "narrow is the way that leads to life, and few there be that find it; but broad is the way that leads to destruction and many there be that find it."