Just wanted to say that I think that using a bottle is the easiest way to get a dreamfeed in. Because the teat is harder than a nipple, it is easier to tease into your baby's mouth, and after that the sucking reflex takes over. It is up to you whether you use formula or EBM.
I was nervous about getting DD to take her first bottle in a dreamfeed, but it was really easy and I am delighted. It means that I can empty my breasts expressing last thing at night and that anybody will be able to give DD her feed now.
As for when to stop dreamfeeding, I guess it must depend on your baby. I remember asking the same question in a poll once and most people seemed to stop by 6 months or so. I was still at it at 9 months! This was partly because our son had allergies and was not getting any other milk in his food, but he was still taking a good feed and was sleeping through the night, so I saw no reason to mess with a good system!