1. Does Bella really understand all that she will give up in becoming immortal? Do you think her understanding is limited by her age, life experience, or something else?
I don't think Bella really fully understood. The main reason she wanted to be immortal was that she craved being like Edward, being next to Edward forever, and basically never having to lose him. She understood that she would have gone through the newborn stage (which never happened) and that meant a lot of pain and emotional stress, but she didnt really consider what it would be after everyone she knew and loved in her human life died. All her friends, her parents would have died and she would carry on. I don't recall Bella actually considering anything like that.2. What do you think Emmett and Jasper were going to do for Edward's bachelor party? Was Jasper telling the truth?
Lol, I really don't think that they would go to a strip club. Also, like everyone else, I don't see a reason for Jasper to lie. They most probably just went for a good old boys-night-out-hunting. Maybe in a very exotic location?
Besides, I can't imagine Edward in a strip club. He just wouldn't be interested, and would just want to get out. Equals pointlessness.3. Tanya made a play for Edward long ago. We don't know much about Tanya, but we know quite a bit about Edward. Why do you think he turned her down?
She probably wasn't his type, and maybe she just was trying too hard
Also, she could have had too many vivid pictures in her head which could have scared him off, lol.4. About Immortal children. At what age or developmental stage would the Volturi allow them to be created? A two-year-old usually understands the word no, but evidently that wasn't enough. How would they determine if the child could "keep the secret"? What would the determining test(s) be?
I think that the age which everyone more or less understands what is right and wrong, and the age which people begin to have a lot more self-control is 13-14. I think that they could determine how they kept the secret by examining people of that age. Say, giving one of them a secret about someone, which would be sensational news. Next, they could start to spread a very very vague rumour about that person. If the "secret keeper" (sorry about HP ref.) resisted all the attention, and kept the rumour, then it would be safe to entrust that child with secrets.