What I was told by our IMs was that (assuming you have a normally devloped, term baby with a spontaneous and naturally progressive labour), the biggest risk in a breech birth is of cord prolapse. As such, frank breech (bum first, legs up) is the preferred presentation as the bum plugs the pelvis nearly as well as a head and so the risk of the cord escaping first is reduced. Full breech (sitting like a budha) is next favourite and footling breech (leg/foot first) is the highest risk option as there are plenty of gaps for the cord to drop down through if it is so inclined.
Re. hips - there is known to be a link between a breech presentation and hip dysplasia. However, when we were trying to decide what to do we were told, again by our IMs, that the current view was that a breech position was more likely to be symptom than cause - ie the baby had hip dysplasia and so chose to stay bottom down rather than the baby stayed bottom down and so developed hip dysplasia. I was given to understand that, as far as they knew at the time, a vaginal breech birth of a frank breech baby was very unlikely to either create or agravate a problem with the baby's hips. If your baby is breech at term it is usual to be offered a hip scan for them at a month or two, regardless of how they came into the world.
Many women seem to be told by their obstetricians that there is a risk in a breech birth that the body will come out and then the head will get stuck. Again, what we were told by our IMs was that in their experience and to the best of their knowledge, there has never been a case where this has happened (worldwide) to a normally developed, term baby with a spontaneous and un-augmented labour. The baby's hips are usually very similar in size to the baby's head, so if the bum goes through the head should follow. They do, sadly, know of cases where it has been an issue, but with babies that have been preterm or where labour has been assisted in one way or another (either chemicaly or physicaly). If you do decide to go for a vaginal breech I would strongly recommend that everyone involved is in agreement on what type of birth or delivery you are talking about as there is a HUGE variation in the way things are handled.
Just to reiterate, I'm not medically qualified in any way, but I did have a breech baby (early 2007) and did way too much reading at the time. We chose the IMs we did because they had a lot of breech experience and, as such, we put a fairly high confidence rating on the information we got from them - but we knew them and that was our choice.
Fingers crossed your baby turns by themselves and this is all irrelevant.