I have 5 children and I must say that weaning each child was a little different. I breastfed all of them for differing amounts of time. My last child very rarely had a bottle. But, my other children seemed to get tired of the bottle the more that I offered them a sippy cup or something similiar. I think that a lot of the cups that they have now still need the "sucking" action to get the fluid out, so in a sense, I think it makes the transition easier. I was never one to say that on a first birthday the bottle should be gone, but I do know mothers that have done this. I guess I was lucky that just my offering a cup more often was enough for my kids. There were older than one year when they were completely done with the bottle, however. Maybe 18 months at the latest. I think that I did do a little bit of "oh no, your bottle is broken" stuff, like cut off the nipple of the bottle, etc. That worked too.
Maybe since your daughter was premature she should have a little more time anyway.
As far as the second step formula... my sister has a daughter that is lactose intolerant and used the second step formula in her sippy cups until she thought she was ready for regular soy milk. She thought that it was great.
I hope I have helped a little. Good luck!!!