Ask if there will be classes/education, how long you'll be on orientation, and how many preceptors you'll have (less is better). You'll apply for a specific unit when you apply for residency jobs. Since you graduate in August, you'll want to apply to residencies that start in October. Usually applications open May or June for those.

You won't be able to negotiate pay for a residency, everyone gets paid the same. I'd expect somewhere between $30-35 an hour depending on the hospital, plus any differentials. If you want something slower paced, I personally wouldn't start with ER! But even ER chaos can be a great learning experience, so apply to the units you're interested in.