Well keep in mind that most ERs will prefer FNP due to the ability to see children. However, many NYC hospitals have pediatric ED separated from adult ED, however, again ED is typically marketed as FNP opportunity so you may have some difficulty getting past recruiters. It's not impossible, though. You would be wise to advise interviewers that you do not see children if you are an ACNP. It would be bad if that were a surprise and you are asked to see a pre-pubescent child.
(As an ACNP myself, I'll see a child as long as s/he has reached puberty and it's not a super specialty problem, e.g. leukopenia in a 13 yr old cancer patient. There's nothing saying ACNP can only see 18 and over).
Furthermore, some EDs have the PA/NP staff cross cover adult and pediatric ED. Not many, but some do. Many EDs - especially private groups like Envision (which encompasses former companies like EMA, etc.) - have quarterly productivity bonuses in addition to salary. As a new grad you could probably start with ~ 120k. ED is usually three shifts per week too, so if you wanted to do a fourth shift every so often after getting acclimated and getting into the groove of the provider role, you could make extra. After all ED is one of those where help is always needed. If you ended up doing a fellowship like at R. Adams Cowley Shock Trauma Center you could probably get more money, but obviously during the fellowship you'll make peanuts. I do not know anything about psych.