You can find these under the translations of the following files:
/administrator/language/en-GB/en-GB.plg_app_user_blog.ini
/administrator/language/en-GB/en-GB.plg_app_user_discuss.ini
They are using the following language strings:
APP_BLOG_USER_TITLE="Blog"
APP_DISCUSS_USER_TITLE="Discussions"
As for changing the icons, they are available in the following locations:
/media/com_easysocial/apps/user/blog/assets/icons/small.png
/media/com_easysocial/apps/user/discuss/assets/icons/small.png