I don't give my birds "special" foods when they're breeding, just more of what they usually eat. But their regular diet includes some soft items, and they have a very strong preference for the soft foods when they have babies in the nest. I think this is their natural instinct speaking, telling them to feed soft foods instead of dry seed. I give them as much of these items as they want in several installments throughout the day, with one exception - the quantity of cooked egg is limited.
You can give the parents cooked rice, but you don't want them to limit themselves to just this one item because that would be nutritionally unbalanced. Find a variety of other soft high-nutrition foods that they will accept and offer those too. I would avoid the pasta unless it's whole-grain - if it's ordinary pasta it's pretty much empty calories. With whole grain pasta you want something that's not enriched, since enriching adds too much iron and zinc for birds.
You can soak or sprout your birds' regular seeds to make them softer and more digestible, and also grains from a natural-foods grocery. There are instructions at
http://talkcockatiels.com/showthread.php?t=9019 Be extra careful about avoiding spoilage since babies are involved.
Besides the sprouts and veggies, my birds' favorite baby foods are organic multi-grain bread (you want something that is NOT enriched) and Harrisons pellets. Pellets are an excellent baby food - the parents eat them then drink water to soften them up for the babies.
A couple of things to be careful about: I'm generally OK with the use of grit (oyster shells in your case) but I don't think it's such a good idea when you have little babies in the nest. I know someone on another board who lost a whole clutch of cockatiel chicks because the parents regurgitated grit to them and impacted their crops. Your birds need a lot of calcium at this time but you need a source that's less chunky and easier to digest, like cuttlebone. If your birds will eat pellets, they'll get calcium and other minerals that way.
The vitamin drops in the water are iffy too, since the dosage is unpredictable and they can promote the growth of bacteria in the water. It's better to let your birds get their vitamins from natural sources (plenty of veggies will do the trick) and from pellets if they will eat them. If your birds have never eaten pellets before then you can expect some resistance, but there are various ways to try to entice them into trying the pellets.