She'll learn step up as she grows, just press gently against her chest and say 'step up' and then when she does it give her lots of praise... but if she's still a little wobbley it might be a little difficult.
As for the toes, my guess would the same as Buddy's. My friend has a clutch of baby Jardines right now and one of them is missing a few toes, her guess is the parents bit them off when he was young. If they weren't bitten too high up I think the nail still might grow with some time but I think it depends how high up they were bitten... unless it's a birth defect.

They adapt really well to different problems so it shouldn't be a problem in the future but she'll probably have some issue with perching as she won't be able to grip as well as a bird with toenails would, I'd definitely recommend some flat perches like this
one (look for 'handicapped perches' or 'flat perches' or 'special needs perches' or
birdontherocks Casey has a manzanita flat perch even though her feet are normal, she loves it and it gives her feet a break from perching.

I wouldn't think she would be eating her own feet, they do chew on their feet when they groom etc. but I'm not sure... Good luck, hopefully some others have some more insight!