I have had good luck with feeding babies what ever mom is eating.
I have fostered several litters from about 1 week old to 4-5 months old.
I kept the babies and mom all together until about 3 months, then all the boys got neutered and mom got spayed. Around 5 months, the little girls got spayed.
Some mom's would wean the babies on their own, other mom's would let them nurse even when they where as big as her. You can monitor their feeding, and decide to remove them if mom is not weaning them herself.
You should notice that when the babies approach mom and try to feed, she will flatten her tummy to the ground so the babies can't get to her teats or she will jump up and run away.
As for feeding veggies, I feed one veggie at a time, starting with small amounts. Then monitor for about 48 hours before introducing another one. None of my foster litters had bad reactions. All of my babies where eating greens by the time they where eating solids.
It seems that while they are still nursing, the anti-bodies help the babies to digest the greens.
However, if you want to play it safe, then keep the babies on pellets and hay until they are older (5-6 months).
--Dawn