Well....you asked a question and you got answers. Being a medic in the military while it will give you an edge....is completely different than your role as a nurse. You asked if you might be over your head as a new grad and didn't divulge that you have experience in the medical field.
MOST new grads will find the ED challenging. The pace the acuity, the drunks, the crazies, the codes are way beyond the non ED nurses roles. Even ICU nurses struggle with the ED for volume and juggling patients and priorities. Even you will find the pace, policies, rules organization challenging as a new RN. I have seen very experienced street medics really struggle in their roles as RNs' for it is vastly different than being the RN. Medics are far more independent (for the most part) than nurse are allowed to be.....especially when you are the new kid on the block.
While your actual skills for IV's and labs will definitely be a bonus, you will be expected to act as a new grad. Just a friendly reminder.......Reminding everyone about being a medic will not ingratiate you to the seasoned nurses hearts. You are the new guy.....fresh out of school.....like it or not and act accordingly. I know this is second "40ish" career for you but you are the "new grad" and those ED nurses will help you to learn and rememver that accordingly.....My advice? Tread lightly and kindly.
I want a nurse new or old who recognizes their limitations, acknowledges their shortcomings, and are willing to learn...... for it makes them a much safer competent nurse. New grads in charge of the nursing homes? Irresponsible, but that is the nature of the beast these days and it's all about the money. That poor new grad doesn't realize the risk/responsibility to her and her license and the Administrators.....like it that way. Sad really.
Good Luck on your new position and I wish you the best on your new nursing journey. Peace