hey james,
for the language strings you can use joomla's native language override function - that way even with an update you don't have to make your language changes over and over again. you can find more informations here: http://stackideas.com/blog/how-to-override-joomla-language-strings

for the group permalink field you can change the field value at your easysocial backend -> groups -> categories -> then click on he group category where you want to change the permalink handling.
if you have the group category open click on the "custom fields" tab and select the permalink field - at the right side you then see the configuration possibilities where at "core" you can set required to NO.

hope that helps and have a nice day