What's the max number of objects you can put into a stage?
I don't know. I think it's completely dependent on file size limits of the stage.
How do you tell what the file size limit is? o_o
BAH with your file sizes
to answer, I dont know if someone has put those limits up as a reference. But I know for a fact that Riivo has no size limits, and you can put whatever you want on your stages.