Hi Ira
There is some detailed documentation of the web service functions available to Moodle 2. You need to login as admin and go to Site admin > Plugins > Web services API documentation.
This will give you and idea of what can be controlled by the web services including the following functions.
These won't be available to Totara 2 is released but it would be good to read the detailed documentation of any functions you might consider using.
core_course_create_courses
core_course_get_contents
core_course_get_courses
core_enrol_get_enrolled_users
core_enrol_get_users_courses
core_files_get_files
core_files_upload
core_group_add_group_members
core_group_create_groups
core_group_delete_groups
core_group_delete_group_members
core_group_get_course_groups
core_group_get_groups
core_group_get_group_members
core_message_send_instant_messages
core_notes_create_notes
core_role_assign_roles
core_role_unassign_roles
core_user_create_users
core_user_delete_users
core_user_get_course_user_profiles
core_user_get_users_by_id
core_user_update_users
core_webservice_get_site_info
enrol_manual_enrol_users
moodle_course_create_courses
moodle_course_get_courses
moodle_enrol_get_enrolled_users
moodle_enrol_get_users_courses
moodle_enrol_manual_enrol_users
moodle_file_get_files
moodle_file_upload
moodle_group_add_groupmembers
moodle_group_create_groups
moodle_group_delete_groupmembers
moodle_group_delete_groups
moodle_group_get_course_groups
moodle_group_get_groupmembers
moodle_group_get_groups
moodle_message_send_instantmessages
moodle_notes_create_notes
moodle_role_assign
moodle_role_unassign
moodle_user_create_users
moodle_user_delete_users
moodle_user_get_course_participants_by_id
moodle_user_get_users_by_courseid
moodle_user_get_users_by_id
core_course_get_contents
core_course_get_courses
core_enrol_get_enrolled_users
core_enrol_get_users_courses
core_files_get_files
core_files_upload
core_group_add_group_members
core_group_create_groups
core_group_delete_groups
core_group_delete_group_members
core_group_get_course_groups
core_group_get_groups
core_group_get_group_members
core_message_send_instant_messages
core_notes_create_notes
core_role_assign_roles
core_role_unassign_roles
core_user_create_users
core_user_delete_users
core_user_get_course_user_profiles
core_user_get_users_by_id
core_user_update_users
core_webservice_get_site_info
enrol_manual_enrol_users
moodle_course_create_courses
moodle_course_get_courses
moodle_enrol_get_enrolled_users
moodle_enrol_get_users_courses
moodle_enrol_manual_enrol_users
moodle_file_get_files
moodle_file_upload
moodle_group_add_groupmembers
moodle_group_create_groups
moodle_group_delete_groupmembers
moodle_group_delete_groups
moodle_group_get_course_groups
moodle_group_get_groupmembers
moodle_group_get_groups
moodle_message_send_instantmessages
moodle_notes_create_notes
moodle_role_assign
moodle_role_unassign
moodle_user_create_users
moodle_user_delete_users
moodle_user_get_course_participants_by_id
moodle_user_get_users_by_courseid
moodle_user_get_users_by_id
regards Craig