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?
She understands, in the abstract sense. But yes, I really think her understanding is limited by her age. She truly doesn't understand Rosalie's desperate desire for a child - although she is very mature for her age in some ways, in others she is not (as Rosalie comments in Eclipse). And although she's made the decision that she wants Edward and doesn't care about children, she isn't yet old enough to understand that fully. And whilst she won't mature physically from the moment of transformation, she will mature mentally & emotionally and she might have one day become broody - it;s nto something you can predict in any way.
From some of the comments I've read, on the Lex and elsewhere, I think that this is something many younger readers don't truly understand. 2. What do you think Emmett and Jasper were going to do for Edward's bachelor party? Was Jasper telling the truth?
Yes, definitely - it's their idea of a good night out. Mountain lion & grizzly are their version of a good steak & wine!
And who needs paintball or clay pigeon shooting when you get to hunt dinner?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?
He just didn't feel the same way about her and, being a gentleman, he wouldn't lead her on for temporary physical gratification when he didn't want to be her mate. There's more about their relationship in the Midnight Sun draft.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?
They would have to be old enough to have control of themselves. I think Jane's character is only just old enough - her petulance and near-tantrums are a sign of her youth. Any prepubescent or pubescent child is unlikely to be emotionally mature enough. As they will never mature again physically after the transformation, they also need to be physically mature or near it (anyone remember the girl vampire in Interview With a Vampire? Very old, mentally mature, falling for adult vampires but stuck in a childs body).