That's correct-- no veggies and definitely no fruit until at least 12 weeks of age. Since your Flemmies will be babies for even longer, it wouldn't hurt to hold off until 4 months before offering greens. When they are old enough to offer greens, dark green lettuce is just fine. Romaine, red leaf or green leaf lettuce is just fine. Iceberg has no nutrition so there is no point to feeding that. When they are older, the greens should be introduced slowly, but Inle-rabbit's links explain all that.
As for the pellet food amount, usually babies are free fed pellets. The only exception would be if they are over-eating the pellets to the point where they are not eating their hay (or eating very little hay).
Just bear in mind when you read about the diets of rabbits, there is a difference between adult and juvenile diets. Typically the juvenile diet ends around 6-7 months of age. But not so with Flemish. They will continue the juvenile diet until roughly 10 months (some say 1 year).
It isn't unusual for such young bunnies to get along, but as others have said, that can all change with the onset of hormones. Those hormones can cause formerly snuggly, cuddly bunnies to turn on each other and fight viciously. I never consider baby bonds to be true bonds for this reason.
Bunnies bond best when both are fixed. Males can usually be altered at an earlier age than the females which is rather convenient since it can take 1 to 2 months after surgery for the boy's hormones to settle down. It is usually best to wait out the 2 months post surgery before attempting any bonding. You can check
this page on my rabbit site to see a couple different methods for bonding (for when the time comes).
Oh, and just to be fair, those hormones can affect their behavior towards you as well. So don't be offended or think something is wrong with your rabbit if one of them starts getting nasty or grumpy. My site explains some of this but not to worry- fixing them will take care of hormonal behavior.