Zenn, I am glad you are trying to plan this out and work out a plan for the separate ages. Personally, I am not a fan of cards (no pun intended) for children. If you really have to do cards, then try and make it something visual instead of having them memorize a card and try and follow along.
So far you haven't worked out the patter correct? Well until you do-- you really won't know how long your show is. I actually do this in reverse. I actually come up with the storylines and patter FIRST, then pick out the tricks to fit the patter. That way I know the show is original, true to your own "persona", and you will find you save yourself money on unnecessary tricks in the long run. This may or may not work for you, it is only a suggestion.
Another thing that came to mind (we have it, haven't used it) for the kids is the good old newspaper tear-- just use the funnies. It is very visual, easy concept for the kids to follow, and has a pretty big impact when you think about it.
Keep up the process and let us know how things work out!
Wishing you all the best,
P.S. I also think 3 minutes for D'Lites is too long. I think the longest Danielle ever performed them for was about 30-45 seconds and it was just for a dramatic opener for her stage show--- she walked on stage with only backlighting so her silhoutte showed while she performed them.
I was also thinking on the 3rd-5th graders, you may want to switch up the cup and balls routine to the 3 minutes and Rocky for the 5 minutes. The kids could get a bit restless with the cups & balls but if you have an energetic and comedic routine with Rocky you can keep them easily laughing for 5!