Don't worry about too many questions!

You don't want to make any major switches in the beginning since he is still getting used to everything... but eventually you'll want to switch him over to a pelleted diet, which is healthier for them. Quakers are prone to Fatty Liver Disease, and seeds are much higher in fat and should be fed in moderation as treats, not a main diet.

Below you'll find Andies Conversion, but again, you'll want to wait a little while before trying it.
http://www.quakerparrots.com/forum/index.php?showtopic=1366All those foods are fine. Grapes you might want to use in moderation since they are very high in sugar.

Also, you want more vegetables, again because of the amount of sugar. Some Quaker favourites are: sweet potatoes, mashed potatoes, melons, corn, strawberries, pastas, rice, broccoli, papaya, chicken, egg, etc. I know that most aren't a fan of Carrots! Casey will only eat them once in a while streamed in little tiny chunks that fit in her beak!

To find out what foods they like and dislike you have to just keep offering as they might not like it one day and a week later they have changed their mind!

Some prefer them served in different ways, ie. match-stick form so they can hold it, or little chunks that they don't have to touch or mashed or different shapes... you just have to figure out what they like best.

Basically anything we can eat they will want to taste! Just don't let Jack have avacado, it's poisonous!
Below is a link to a Nutrition Table.
http://www.quakerparrots.com/diet/food-nut...le-for-parrots/Have fun!