Please see below:
1. want to remove the “slider option” module from user options but still want the default choice “full slider” to be selected?
—> You can remove it from wpestate/templates/front-end-submission.php
2. i want to add some text that could be translatable (with plugin Localization): for instance, can you tell me please how to add the word “bonjour” and make it translatable?
—> look for one that is already translateble and copy the code.