@MeadowHay firstly - don't panic!
It's normal to feel anxious, I've spent 15 years reassuring parents that all will be well (and it genuinely normally is!) but when my own DD started nursery it just felt like such a different ball game, complete anxiety!
So, to try and answer some bits;
- Settling in - yes I feel they're worth doing, not sure what your nursery offers but we ask parents to stay for the first hour - let's baby see parents in same environment/explore together and then the second session of 2 hours - we let parents decide to stay/go/half and half. This is normally enough but some children do need more and if your daughter is particularly clingy and you're in a position to I'd ask for a prolonged settle - pay for some extra half day sessions maybe a month before you need her to start properly.
Little and often may be the best way for her to start
I know it's not nice to think of them crying but personally I find children settle easier if we're given the time to settle them, they need to know that we are a new source of comfort, so yes there may be crying and upset and for some even hysteria, but short lived it normally is.
Of the couple of children who never settled - both remained in nursery as the parents had no choice and they knew child was fed/watered/clean/healthy/not poorly so nothing missing etc in their care, and sadly was just 'them' I will add, they would settle for longer and longer but we just never got to a complete no upset stage, but it did lessen over time
Pattern wise - because you're looking at more days overall this will likely help anyway, it's usually a struggle for the children who just do 1 day, but the broken pattern works nicely from a parent perspective, I know I feel better that my daughter has days off in between for family time 
Sleeps - it's true that sometimes there's just a magical air in nurseries for sleep lol my own daughter refuses day sleeps but off she pops happily at nursery! I would say be open to let them try their methods in the first instance, as you genuinely might find she doesn't need a pushchair - but if ultimately that's what she does then the nursery should be able to provide that even on a 1:3 ratio basis. We used to keep a pushchair indoors at an old nursery as needed.
I think the biggest thing I can say is just try and be relaxed and open, it's highly likely that she'll settle given time - maybe not after a day or two but hopefully 2-4 weeks you'll see some improvement