The Lake of Fire is the Second Death. In my opinion it makes more sense for this to be annihilation than eternal torment. The terms commonly taken to mean it lasts forever were also used to describe the destruction of Sodom and Gomorrah, which are not still burning.
The bible does not exactly mention Hell. It mentions Hades and Gehenna. Gehenna is literally Jerusalem's garbage dump/open pit trash incinerator, and was probably used as a metaphor for complete destruction. I consider Gehenna and the Lake of Fire to refer to the same thing.
Hades literally means "the unseen," and commonly referred to everything hidden under the surface of the earth. It includes not only the mythological realm of the dead, but also the places where minerals are mined and where seeds are planted. It is not necessary to assume that it refers to some place in the spirit world where the soul is tortured, when it could just as easily just mean the grave where dead bodies are buried.
The word Hell is a cognate of the word Cellar, and originally had the meaning of a place underground where things were stored. It is a very close synonym with Hades, but I avoid it because of the connotations it has acquired.
The OT "Hell" was and still is "underground". Satan and the fallen angels are not bound there, but that was the place prepared for them to "enjoy" their existence.
One of the first punishments of "The Law" Moses spoke and the earth opened up and swallowed a group of Jews into this place of "fire" and death.
Dead souls were sent there, and there was a division between those who accepted God and those who refused. When Jesus gave up the Ghost, He descended into this area of the "underworld" and led those souls who had "Faith", those who obeyed God's Word and was accounted for righteousness free from the grasp of death and "hell".
Catholics have followed this seperation and called it purgatory, as in a resting place for believers until the place in Heaven was finished as a final destination. The Apostles said that now when one dies they go straight to heaven to be with Jesus and those who were freed from death's captivity. The pre-christ place was called Abraham's bossom.
At the end of time, death and hell will be cast into the eternal "lake of fire".
Yes, Satan can repent and be forgiven.
Suicide is said to be unforgiveable, because one is past the point of "asking" for forgiveness. Is it unpardonable though? I say yes, because even Satan can still be pardoned. There is pardon for those who accept (while alive) and to a degree pardon after death. The one choice that cannot be pardoned is denying the Holy Spirit. There comes a point in every person's life where refusing the Holy Spirit result's in total depravation. God will give man the choice to follow their own desires and that is the slippery slope that leads to men and angels to their own ends, and not the path that God had planned for them.
Even God can be found in hell. That is why it is not really a competition between "good" and "evil". That was what Dante, philosophy, personal opinion, and even the Devil himself want everyone to think. I suppose if one had enough pride in himself that he can do better than God, then he may not be on God's side, but that is not God's choice. God's will is that all come into His presence and give Him due benevolence. Those who put God on the pedestal of a selfish child, are free to that view, however it seems a little petty to me.
Why was God not powerful enough to stop the division? Why does God not force everything to be perfect and flawless? Why is it inherent in humans to divide into class, and all the prejudice in the world? Why is pride even allowed? Seems like there are those who think that they have the answer to these questions and deny that there is even a God.