To answer two issues:
For the price match - you can call them and ask them to price match - you don't have to purchase over the phone - the price match is good for 3 days.
For bing - I read somewhere on one of the sites (maybe slickdeals) that if your bing cashback doesn't post, you should contact bing and/or diapers.com. Supposedly diapers.com is very good about fixing it with bing if you linked through bing before making the purchase. I think on the bing website it says what to do if your cashback hasn't posted (and in what time frame) - good luck!
(I've made two diapers.com purchases and both times the bing has posted within 24 hours, so I'm not sure what happened).
Also, for first time purchases, you can try sending in for this $14.97 rebate (I haven't received mine yet so I'm not holding my breath, but I figured it was worth the price of the stamp to try):
http://www.diapers.com/helpcenter/parenting.htm
And you can combine the first time 10% off coupon with the $10 off referral if you add diapers. Most people on this site have a referral code - just pm