For ages and ages- ergo quite a while, a long time, but a fixed time- not eternity.
Tortured- for me means intense correction which cannot be taken lightly. We see little examples of this when seeing how long correction process takes in our court system. When there are many charges they all have retribution- satan would have many charges, plus the beast would also have charges.
The fire is a purification to burn out the dross, rubbish, impurities, deceits, incorrect values and actions....
Paul makes that observation;
1 Cor 3;15 " If someone's work is burned up he will suffer loss, however himself will be saved, but only as through fire."
The fire also seems to be the destruction/riddance of the flesh.
1 Cor 5;5 " Hand this man over to Satan for the destruction of the flesh, so that the spirit may be saved on the Day of the Lord."
Part of the plan and process of growth and development.
Hope this answered your question.