ffjjj ,
Welcome to Fiction Factor's forum.
There are more than a few Australian writers who visit the forum here, so they may have a better handle on the IRC. I do, however, suspect that the weight of the item would have a bearing.
I'd suggest that you request your short story to be recycled (instead of being returned) in your cover letter. The acceptance (or rejection) should not require more than one.
As for the spelling, I don't think it is that terrible of an issue. I don't believe a few regional variation in spelling would cause a rejection. But if you're aware of the spelling variations, it couldn't hurt to change them, unless the tone and character of the story is better with it.
Good luck.
R-Tech