Officiant help!

I'm contacting officiants for our wedding next year, and am so totally clueless about what to ask! I had pages of questions to ask reception venues, but for some reason I'm blanking for an officiant. I've asked if they are available (duh), asked about cost, and mentioned the style of ceremony we want, but I feel like there's more I should be asking!

For those of you who hired an officiant, did you have him/her attend the rehearsal? Many people I contact charge an extra price for the rehearsal (which makes sense) but state that they don't really need to be there?? And speaking of price, if anyone feels comfortable sharing I would love to know how much you paid for your officiant!

Also, is it normal to not be the only ceremony they attend that day? I know I'll only be with them for ~1 hour maximum, but it makes me nervous that they'll be late or something.