Such as, how many postcards are mailed out per month and how many deals you get from them each month on average?

Once they see that you are initially just trying to inform them of their situation, then you can lead into their options....list the home on the market and hope it sells before the auction date, bankruptcy, or give you authorization to speak to their lender and write an offer that is less than what is fully owed.If they don't want to hear what you have to say..wait until the auction date is assigned and then send them a letter/postcard that has the date stamped in red on it...you may be the first to inform them.

I guess all the flyers, post cards, and signs on the highways help grind it into peoples mind so googling that phrase is just the thing to do.

Or, if you want to wholesale, you can send a lot of postcards for $25K.

(ex. for postcards should we use the exact same postcard repeatedly) Or should we change the content on the postcard after each touch?

I'll say this..... it appears to me that you are sending letters/post cards and you are getting phone calls back.  

hmm i can not fully answer this for your state but in ohio the "normal" starting split is around 60/40 for the agent, unless you go remax or some of the other bigger people who offer a 95/5 but your monthly office fees are like 1000/1500 depending. your best bet is to call up any local broker and go "interview" see what they all say and are willing to offer you.i got my first 500 business cards, 10 yard signs, 2 lock boxes, 3 months of o office dues, and 750 post cards for signing with my broker. so its all about how you handle it. 

Almost 1000 postcards, printed through click2mail per their EDDM spec.

I sent out a pretty stereotypical "We buy Houses" postcard to these owners.

I heard a pretty cool idea for postcard on the podcast the other day (sorry I'm not sure which).