My baby gets Natural Zupreem pellets (he didn't like the fruity kind) in his cage all day. I usually put about 2 tsp in at a time so that I don't have to dump a lot when I give him fresh food (every morning). Every morning he goes to his playstand to eat breakfast. He gets a Kaytee pasta blend with fruit (It comes packaged, you just add water and heat it). I sometimes add vegetables to this. At night he gets the Kaytee vegetable pasta blend with frozen vegetables heated. Every other day I give him a seed mix, about 2 tsp. He also eats a variety of table food including tofu, spaghetti, bread, and whatever else we're eating. He likes to share In addition to this I sometimes cook up sweet potato for him. I tend to stick to frozen vegetables because I know they are picked and frozen right away. (Always get grade A) (Plus it's way easier) I also give him 2-3 Nutriberries every night in his Zupreem bowl. My vet said his diet is "ideal." Not to brag...Yippee!B)
I am actually bird sitting right now for a lady who does the coolest thing. She buys party trays for her birds. The veggies and fruit are all sliced up, washed, and ready to go. If you can afford it every week or so, I think that's so clever! I think the easier your feeding routine, the easier it is to keep up a good one.
And to answer the other question- if it's a wet/fresh food (veg, fruit, pasta) I only leave it out 2 hours. Some say 4 hours, but I like to play it safe.