Chicks won't have any problem with the ramp as long as the mama broody teaches them how to go in and out. They will hop and fly onto most anything in another week.
But there could be a problem with the other flock members trying to pick on the chicks. It's better to have a protective enclosure for the little family while the chicks are so small and vulnerable.
The food is indeed a problem. Older flock members will naturally try to bully the chicks away from the food. It's another good reason to keep a safe enclosure for the chicks and broody, although it's her job to protect her chicks. Some are more than up to it, but some are not.
You're off to a splendid start with the chicks growing up withing view of the flock. They will be accepted into the flock very quickly and the need for a protective barrier between them and the rest of the flock won't be needed for long.
As far as feed goes, it would be best to have everyone on the same feed as the chicks. Everyone can eat an all-flock grower ration or they can also all eat the chick starter for the next several months with no problem as long as the layers have access to oytser shell on the side.