2) The abuses were much less than most people think. For a good account see Warren Carroll, The Glory of Christendom (part of a seven volume series the data below is from his work) on the Inquisition, and on sad abuses by the Popes in the Middle Ages. Further all governments of Europe around this period severely punished heresy. In England, the offender, often a Catholic priest who had merely said Mass, was hanged, drawn and quartered while still alive.
In France and Spain especially, the Cathar heretics were a danger not just to the Church, but to the state, and to all. In 1229 a council at Toulouse required that everyone in Languedoc, where most of the Cathars were, to take an oath and renew it every other year, to remain a good Catholic, and to denounce heretics. But Cardinal Frangipani heard testimony from a former Cathar, William of Solier, who said that to make such names public would endanger the lives of the informants. Out of this grew the Inquisition, established by Pope Gregory IX in 1233 to be staffed by Dominicans. The Cathars then were as dangerous as terrorists today, and brought fear, cruelty, bloodshed and war wherever they had sufficient numbers. In southern France it took the full armed power of the King of France to overcome them.
But then they went underground. Persons accused by the Inquisition were not allowed to know the accusers, to protect the accusers this sort of thing happens in protection of witnesses in U. S. courts today. But the person arrested was to make a list of his personal enemies and none of their testimony would be used against him. What modern court allows such a thing? Torture was used, but quite infrequent, and not lasting in its effects. In the 50 years of the operation there were no more than 5000 executions, which was small in comparison to the total executed for other crimes in the same period. Some Inquisitors did abuse their power, but they were promptly and strongly curbed by Pope Gregory IX. In 1242 the Cathars murdered ten of the Inquisitors.
As to the Spanish episode, the Turks in 1480 attacked the south Italian city of Otranto. 12, 000 people were killed, the rest made slaves. The sacred book of Islam does call for killing all “infidels” (The Koran says: When ye encounter unbelievers, strike off their heads until ye have made a great slaughter among them, and bind them in bonds. . . .” cited from B. Palmer, Understanding the Islamic Explosion, Horizon Books, 1980, p. 36). The Turks killed every cleric in the city and sawed the archbishop in two. So Queen Isabel sent a fleet to Italy. In September of 1480, when it was clear the Turks might do the same to any coastal city, Isabel established the Inquisition. It dealt with the special problem of those who pretended to become Christian, but were not really converted, and might open the gates of the city to the Turks.
Torture was used only occasionally and it was the government that inflicted that and death, after the Inquisition turned them over. The Inquisition had no authority over practicing Jews and Moslems, only over professed Christians suspected of being fakes. After the appointment of Tomas de Torquemada as Inquisitor General in 1483 its tribunals were so fair that many preferred to have it hear their cases rather than the regular courts. Again, those questioned could not see their accusers, but could make a list of their enemies, and all testimony from them was discarded.
We must remember again that every government in Europe punished treason and heresy by painful death. Yes, the Inqusition is to be blamed for some things, but not as badly as the legend says.