i made a few things out of gumpaste (number topper, flowers, and "string"), now what? how should i store them? how long do they last without cracking? how about putting them on the cake? its tuesday, cake is for saturday.....

They should last a long time without cracking. Keep them away from moisture and keep them covered so they don't get dusty or fade.

When you put them on the cake, as long as they're all the way dried, you can put them right on the buttercream and they won't soften or wilt or anything like that, even in the fridge.