Jesus dying does nothing to change God's character - the entire Jewish religion and ordained holidays is a hint and symbol of Christ's sacrifice, and it was God's plan from the very beginning of creation. Even in the garden of Eden when Adam and Eve sinned you have a hint at Christ's sacrifice as God clothed them from animal skin - this was, in essence, one of the first sacrifices as a symbol to cover their nakedness/shame. We are all still going to die, and many people will suffer, and there are punishments talked about by Christ himself as consequences of certain actions - not to mention the things mentioned in Revelations and attributed to John who had full knowledge of Christ and even perhaps some more understanding than any of us about the events. It would seem clear that there will be wrathful interventions and direct punishment of sin. However, though this body will pass away, there will be a future life to live - that's the promise of Christ for those who have accepted Him. We're not there yet, we're still in a world and state of sin, death, destruction and decay. Christ's sacrifice certainly doesn't mean any have free reign to sin, or that there will be no consequences for our actions anymore!
As for your reading of Exodus 7, as I said earlier I do not believe it necessarily entails purposefully violating Pharaoh's free will - though I do not doubt God works in the world in mysterious ways. Many scriptural commentators agree that God did not violate Pharaoh's free will, only magnified his own stubbornness. In an effort to understand this perspective, take a look at the following:
http://www.studylight.org/com/guz/view.cgi?book=ex&chapter=007
And
http://www.sacred-texts.com/bib/cmt/clarke/exo007.htm
and
http://www.billmuehlenberg.com/2011/04/20/difficult-bible-passages-exodus-73-4/
There are far less sources that I could find which imply that God was forcing Pharaoh to act. The act of 'hardening the heart' doesn't seem to entail action - God is simply showing here that the result of all of this is that this will come to pass and God will fulfill His promise of delivering the Israelites in spite of pharaoh's actions.