Freelance reporters' hourly rates and fee/page covering last minute add ons or overflow work?

As a freelance reporter, when we pick up last minute requests from agencies looking for a job to be covered, what is the proper procedure on discussing rates per page as well as hourly rates?

Just ask 'em!  What's the rate?  When do you pay?  Do you pay copies upfront?  Do you pay to ship exhibits in? 

Once you get set up with them, they should send you a packet with their format preferences, copy order sheets, worksheet, how to send in your job, and preferably even a rate sheet so that you can keep it on file should you establish a continued working relationship with them.

I don't work outside my agency as often as some of my friends do, who are pros at it, but I have found, agencies will even offer if they haven't worked with you before just to be sure there's no misunderstandings and to make sure you want to take the job.  I'll usually accept the job, before rates are discussed based on the job type, and they'll say, Oh, and these are the rates for this job, blah, blah, blah.  The last time I did it, which it's funny, I just got paid from it today!  Awesome!, the agency followed up with an email right after we talked with the rates we talked about. 

Nothing at all wrong with asking.   You can even negotiate, if the rate is not what you normally work for; simply say, That sounds great but a little out of my area, I'd like to do it if you can add X amount or for experts I'm used to getting X amount.  

Don't forget to ask if they pay for parking!

If it's last-minute, why can't you take and bill it for yourself?  You're working for so-and-so; however, you're billing.

If an agency is looking for someone last minute, say fine and bill yourself