I'll see what I can do. The payment is 100% handled by https://stripe.com/, no credit card info is stored on our end. They're used by companies like kickstarter and you can read more about their security here: https://stripe.com/help/security
The iphone version of this is in alpha and being tested by about 20 people right now. Main thing slowing me down with it is I had to learn a new programming language to make it. It's using http://ionicframework.com/ which uses angular.js, if you come across anyone familiar who wants to help let me know!
There is an API available if you have someone who is willing to code something up. I don't know if there is WebHook capabilities to do a broadcast as soon as something is created but we have a bot respond to a command to pull basic information about games scheduled for the current day. There's some documentation on the API here:
https://www.gitbook.com/book/mlapeter/the-100-api/details
And you'd need to reach out to Mike to get a token created for your group.