I think 911 experience is highly preferred, but not required?
But realize you'll be competing against many EMTs with a few years 911 experience. I do see the occasional new EMT go straight into the ER, but they always have some kind of ER contact that hooked them up.
As far as 911 jobs, it depends on your area. In LA, it tends to take a few months to get hired on at a 911 company. Depends on your persistence, how active you are in calling and visiting them, social/professional ability and vibe. I know of people who keep getting told there aren't openings, but then another person who's a go-getter comes in and gets an interview (without an "in"). Also, not all companies want IFT experience...some view it as a negative (since there's a good chance you learned bad habits at the smaller companies...stereotyping, yes).