If you are having problems sending to large groups, in phone settings, set Group Messaging to "off". If it is on, it will try to send as MMS and be unable to do so for large groups.
Mail is the best way to submit a support/feature request. Please include as much information as you can including (as applicable) iphone hw/sw version and carrier. Thanks!
The jqTouch library is a jquery plugin for mobile development. Included with it are several niceties that sped the development by making it easy to make my app LOOK like an iphone app. There are several other great mobile dev libraries/plugins available. Honestly, I went with jqTouch because it was the easiest to use given my limited UI requirements.