Hi imamul,
Thank you for choosing our theme.
1. After activate child theme you have to rearrange widgets this is issue of WordPress, i don’t know why this issue have a long time they no fix
2. You can use Loco Translate plugin http://support.janstudio.net/forums/topic/theme-translation/
After install plugin you go to Loco Translate > Themes > Claue > Add new language > English(Us)
search Size Guide and change to the text what you want.
3. You change change text “Add to wishlist” in YITH plugins > Wishlist http://take.ms/8GGe4
You can change icon to text by add custom css code in Claue > Theme Option > General Layout > Custom CSS
4.You can add your content in Claue > Theme Option > WooCommerce > Product detail setting > Extra Content
Best regards
Harry
Premium Wordpress themes and plugins, Best WooCommerce theme https://themeforest.net/user/janstudio/portfolio?ref=janstudio