If you've been behind as I have in sending your work out for publication, Diane Lockward's delightful and useful blog Blogalicious has lists (with links) to literary journals that read in summer. Thanks, Diane! I may actually catch up.
Except of course for the revising part. I will never catch up with that.
Prose poem or flash fiction? The line is fine, maybe there isn't one. On The Book Baby Blog they refer to it as "the art of compression and surprise." I think that describes a good poem, but maybe to you it's a good story. Yes to both. Whatever it is, I'm going to be practicing more of it. I love prose poems when they compress language and have the chewy sounds and vibrant images I expect from poetry. And when they compress a story and have an actual plot. Can you write one in 100 words? Tight fit. 100 Word Story challenges you to try and submit. I just may.