1. Do you think that Dumbledore would have lived if Regalus would not have taken the horcrux?

I think If Regulas lived Dumbledore would not have died. I doubt if Harry and Dumbledore would have even taken the trip to the coast.

Or if Dumbledore would have died then do you think that harry's self blame/guilt would have been less then it was in the book?

I think Harry's guilt would have been just as heavy. Harry has a savior complex and with that a tendency to take the loss of loved ones to heart, even if it is clear that other factors caused the loved one to die.

2. Do you think that Draco would have gone to the "good side" if the Death Eaters were not able to come up the tower so soon and then they would have escaped on brooms and it would have ended up with Dumbledore not dying or would they have escape would Dumbledore want to stay for the fight to help all the people he could?

I dint think that Draco would have gone to the dark side. He seems to me like a person that has too much to lose if he did defect to DA. He loves his family and his status and would want to make them proud especially after his father failed. I do not think he would have killed Dumbledore, he seems to have had compassion for Dumbledore as a grandfather figure meddling in his affairs. Had the Death Eaters not come Draco would have let Dumbledore escape.

However, word around the campfire is that Draco can do occlumency. Is this true and where in the books do we learn about this? Draco would have to know occlumency to lie about letting Dumbledore escape.

3. Do you think that fleur and bill would have gotten married and gotten Mrs. Weasly’s blessings if bill would not have been attacked?

Yes, they love each other every much and Bill is a bit of a rebel so he would have married the woman he loved with or without Mrs. Weasly's blessing.
4. Lastly do you think that Tonks and Lupin would of started going out and gotten married latter if Bill had not been attacked and/or if Dumbledore would have not died?

Yes, Lupin seemed dead set in his ways and strikes me as a character that has to be effected profoundly in order to change is views on an important matter. Tonks while a strong character in her own right surprised me by not fighting more for the man she loves on her own.