You've gotten some good advice here - I skimmed most, Cate and LittleTurtleKnits gave some good input (not to slight others - honest! there was lots of good stuff!).
Toby is nearly 4, he was a 26 weeker who spent til 1.5 weeks before his due date in the NICU, and he was only recently weaned (which I only did b/c it was easy to distract him, and b/c he was mostly playing with my boobies rather than eating which I just found irritating LOL).
Toby first suckled at my breast at 32.5 gestational weeks. He nursed once a day til he came home. At that point, I *GRADUALLY* (repeat, gradually) upped the nursings and decreased the bottle feeds. It took a few months after homecoming for him to be completed nursed.
Firstly, I would not worry too much about bottle vs. breast in the NICU. What you want most of all for there to be one or two solid nurse sessions a day until they come home. Preemies are highly inefficient at nursing - it takes a lot of energy (i.e., calories) for them to BF. So your goal should be a bit of practice for the three of you, and some good nipple stimulation for you, until they get home. I was never able to get any noticeable breast consumption while Toby was in the NICU - ie.., weighing before and after nursing, the scale never noticed much milk consumption. Either he wasn't consuming much, or more likely - it's just a lot of work for preemies to nurse- so they use up calories as they consume them at the breast.
A long way of saying - do NOT worry too much at this point about them getting bottles. Preemies do not act like full term babies as far as "nipple confusion" goes - and a big job of theirs at this point is to grow and get big and healthy enough to come home. There's loads of time after that to convince 'em to nurse full time.
The whole nipple-confusion "worry" is based on behavior of regular full-term babies, not preemies. Preemies are not simply little full term babies - they act differently, and developmentally - in my opinion nipple-confusion is a later worry than one that occures during pre-term baby developmental phases.
Once they get home - go from the once a day nursing, to three times a day for a few days, to four times a day for a few days, to 5 times a day for a few days...etc. Continue to do some bottlefeeds.
It took immense patience to get Toby nursing full-time, but it is possible. Partly, we lucked out - Toby was definitely "into" nursing. Partly, it was a whole lot of hard work - it is probably my hardest, biggest accomplishment in my life. (This from someone who has run two marathons and written a dissertation....getting Toby to nurse full time was a lot more work and took an immense amount of patience).
Toby was an incredibly pokey slow nurser for MONTHS. He would nurse for an hour and 15 minutes, and then want to start again 45 minutes later - he was on a two hour schedule of eating, where he was nursing for more than half of it. It was exhausting. As a 26 weeker, he was on the other end of the pokey, inefficient scale - yours are on the same scale, but you can expect them to be a little better
And as for visiting every day- it's worth it. Ask the hospital social worker if they can give you parking vouchers, or maybe meal vouchers. (We got free parking; we went to another hospital for a Toby surgery a few months ago and got free meals too).
La Leche wasn't much help for me, tho I wouldn't rule them out. The ones in my area didn't have much info re. preemies - they kept telling me all the full-term stuff re no bottles etc. and that just wasn't feasible (or correct in my opinion). I DO think that there's a lot of variability in terms of what different La Leche folks say/know/do - so by all means, pump them for info.
And lastly - find your own lactation consultant. The one in the hospital where Toby was born was phenomenal, and she worked really well with both the regular nursery as well as NICU babies. You can hire your own. It'll pay off in the long run.
Kudos to you for doing such a good job - and keep us posted
-- Sara