what if i end up .25 short, will i get the $10 back?
No you won't, I suggest you purchase an avatar or a theme perhaps to make up the difference.
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it says it ends april 1, but u can still spend $50 or more on april 1 and still get the extra $10 right?
I wouldn't risk it. I would make sure you spend the 50 before April 1st, since it could technically be done by 12.00 AM on April 1st.