Most submissions are reviewed within 6 weeks. If the story shows merit, we will respond with a "maybe" letter, explaining that the submission is in the running for a spot in the next issue. At the end of the submission cycle, which is always two months before the next issue comes out, all "maybe" submission are re-reviewed, and the top eight selected for publication. At that time, all accepted authors receive contracts to sign. Since these contracts and, later, the payment checks, go out by snail mail, it is VERY important that all submissions include a snail mail address.
We don't "buy ahead". By that, we mean that ALLEGORY purchases only the stories it needs for the current issue, rather than stocking up for the next and the next. This means that every author who received an acceptance from us will see their work on this site with the next new issue, provided he or she reads, signs, and returns to us an unchanged contract.
Simultaneous submissions are "OK", provided that you let us know at the time of submission that other editors are reviewing this work.
That's about it. Good luck.