Hi Nicola!
I apologize for a slow reply – was out of town for a long weekend.
I am not sure if I understood you correctly – date, tags, and comments are displayed with each post in any case (see e.g. https://satoristudio.net/fuji/success-comes-to-those/ in the theme preview).
Regarding your second question – there are several WordPress plugins that provide the possibility to add social sharing buttons to all posts – I’d recommend Social Buttons.
Sincerely,
Andrew.