Hello!
1 - You can use any effects you want on the spritefont object; however, in this version, you cannot control specific characters. But you can trigger effects when certain words are typed, chosen by you (or by the player if you have a system for that, which would be to get a string that the player typed and put it in the array in the correct place).
2 - Yes, you can. There is a variable that corresponds to who is speaking. After choosing the location of the balloon where you want the image to appear, just create it, and in each speech, change the animation to the name that corresponds to this variable.
3 - Yes, you can use it that way if you want.