1. Their purpose of building a tower was for it to reach to Heaven.
2. Well it probably angered the Lord because in the temple they were probably performing heathen rituals and worshiping idols. I'm not quite sure they were necessarily building a tall building that would hypothetically provide a physical pathway to heaven. I know it says that in Helaman but I don't think any society could be that dense to understand how impossible that really is and this is all metaphorically speaking.
3. The Lord confounded their languages so that they could not continue to be one as a people and scattered them.
4. The Jaredites were a group of people that were shown mercy and were not confounded because they took on the name of Christ.
We are to come to the Savior in Baptism and when we are baptized we take upon His name over us so that we can become like him and adopted into His family. That's one of the main reasons is when we are baptized we are giving ourselves over to Him willingly and knowingly so that if we are worthy of Him we will be found on the right hand of God.
Baptism is only the first step in this and is really only the beginning of the journey back to our Heavenly Father. As we follow the steps of the Gospel and follow after the example the Savior has set for us we are able to make it back to Him because we bear His name and are worthy of it.
