User Mass Info
@oczkers, I've moved to building a JavaScript based AB moving forward since it's much easier for me to separate UI and logic, and I get to steal EA's CSS and images, but I thought I would help with something I've figured out while proxying the web app. There is a new usermassinfo endpoint that gets called which has a bunch of goodies in it all at once, including credits balance and pilesizes.
The URL is not in the site_config.xml, so it will need to be manually added. The current URL is /ut/game/fifa${version}/usermassinfo and it gets called every time the webapp gets loaded for the first time. See here for an example response (it is quite large).
Also, I believe I've figured out a way to automatically detect if the account has the transfer market enabled by looking at userInfo.feature.trade > 0 in the usermassinfo response. I've implemented it in my AB tonight, and will let you know if anybody runs into any issues.