The answer to each of these questions is pretty complex, especially taking into account that the conquest of the Americas by Spain, vs the colonization of North America by the English did not necessarily have the same purpose and the people who carried them out had very different views on how things should be done. As such, the best answers that I could give you would be thus:
1. Were the English colonizers crueler, or more tolerant, than the Spanish conquistadores, would be: both of these were seeking to establish ownership over the lands that had been discovered. However, while the Spanish Conquistadores came in the name of the Spanish Crown and with the support of the Crown, thus also being limited by the Crowns rules and regulations, the English settlers at first were not sent by the English Crown; they came to America seeking religious freedom and new opportunities. The Spanish Conquistadores were not all cruel, and although a lot of abuses were committed, these Conquistadores were also held in check by the fact that they were accompanied by Christian missionaries, whose intent was to evangelize, not exterminate, the Natives. However, the English settlers did not intend to either share with, or mix with, the Natives and their religious views did not necessarily prevent them from being aggressive and discriminatory towards the Indians they met. Some were hostile and cruel to Indians, and some were not.
2. The intermingling of the Spanish with the Indian Natives was due more to the fact that the Spanish only intended to settle and harvest the riches of their colonies and also civilize the Natives they found. Given this, they settled their towns, some of them missions, where the Spanish settled and began to have contact with the Natives. Driven by interest, and also by their desire to civilize and evangelize the Indians, a lot of Spanish intermingled and married with Indian people.
3. The end result of Spanish intermingling not  just with Natives, but also with Africans, and of Africans with Natives, resulted in the enormous racial variety typical of all Latin American countries: pure white, mestizos, mulattos, zambos and pure black people. It also affected societal formation with the societies in Latin America mostly formed into strata that was dictated by origin: purely European ancestry, or mixed ancestry.
