#3
You can call it whatever you want, but if you're using it as a demo to potentially get some industry attention you should have 3 to 5 songs, with your poppiest catchiest hardest-hitting song first. If the first 30 seconds don't have the (professional) listener hooked, they just chuck it. This is a proven fact.
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#4
An EP typically has up to 30-35 minutes of music on it. I did a quick look at all the EPs on my PC, they range anywhere from 4-9 songs. I grabbed Coldplay's Prospekts March EP to see how long it is, its 8 songs and 27 minutes.

In my opinion, once you hit 9 or 10 songs, its an album.
Derpy Derp Derp Herp Derp
#5
if the songs are short enough, it has more to do with play time than the number of songs.
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