Yes, you can get an ED position without ED hours, though a preceptorship in the ED tends to be a helpful shoe in just because they know a little about you. I precepted in an ER, though, and did not get a position there. They liked me just fine, but had no available positions.
I am no help on the "Where to practice" issue- I'm in Alabama and had no intentions of relocating after, so I'm still in Alabama. =)
As for how soon? I precepted a guy just recently who already had a job by the time he got to me, so sending out applications and resumes during the final semester of your school is not a bad idea. You CAN be hired on contingency of having passed the NCLEX within a certain timeframe, and if for some reason you do not pass, depending on your unit's needs, you may just need to take a tech/PCA position until you've passed. I elected not to go that route because I had terrible self esteem and was unsure of if I would pass, so waited until I knew for sure. Obviously, I did pass. =)
Don't stay whetted to the idea of "only an ED" though, because you may not get your first choice of job. I swore I'd never work med surg, and then my first offer was just that. I got a LOT of experience and strengthened my knowledge base that way though.