Round 1: Mark vs. John

I started to read the Gospel According to Mark as my second task after reading the Gospel of John. I thought they would be the same because apparently the Gospels are Jesus' story, and there can't be too many differences in one same story.
What I have been finding as I read is that it does seem like the same story with the same general plot line. However, there are some small differences of what happened and how the story is told. Until now, there are many things that happened according to John that didn't happen according to Mark and vice-versa. Also, the two Gospels agree on some things while they differ on others.
For example, in both Gospels Jesus was able to heal people and even resurrect them. However, the Gospel According to Mark assures that Jesus was also able to perform exorcisms on possessed people. In fact, it was one of his most popular abilities. Like it was mentioned:
 "And at even, when the sun did set, they brought unto him all that were diseased, and them that were possessed with devils. And all the city was gathered together at the door. And he healed many that were sick of divers diseases, and cast out many devils; and suffered not the devils to speak, because they knew him."(Mark 1:32-34).
In John, evil spirits are never mentioned, and Jesus never heals so many people. Jesus' miracles were not so frequent in John, while in Mark (like the aphorism would indicate) Jesus has no real problem in healing anyone that might have faith in him.
Something that came up in Mark that I hadn't seen in John were the parables. The parables (from what I read) was like Jesus' way to spread the word of God in metaphors. For example The Parable of the Sower, were he explains how the good people are ready to receive the teachings of God. Another parable would be the Parable of the Mustard Seed that goes:
"And he said, Whereunto shall we liken the kingdom of God? or with what comparison shall we compare it?

 It is like a grain of mustard seed, which, when it is sown in the earth, is less than all the seeds that be in the earth: but when it is sown, it groweth up, and becometh greater than all herbs, and shooteth out great branches; so that the fowls of the air may lodge under the shadow of it." (Mark 4:30-32).
Again, I found in Mark's Gospel that Jesus chose his twelve disciples, and to them, he didn't give them parables, but gave them the teachings with no complications and even gave them healing and exorcist powers. John never really mentioned were the disciples came from, although he states (several times) that Judas will be the one to betray Jesus. I wonder why both Gospels say from so early in the story that Judas was the betrayer. Maybe the hate him a lot.
There is one part in which the two Gospels are totally agreeing with, which is the part of the angry Pharisees. This part (which if this Gospel is similar to John) will be seen again further on. Probably in this Gospel, the Pharisees will also be the ones who will want to kill Jesus.