Editing the layout of excerpt

Hello everyone,

First, I’m french so sorry in advance for the eventual mistakes. Also, I’m not an experimented developer so please, don’t hesitate to add details to your answer. ??

I would like to change several things in the excerpt.

1) I’d like to have a margin between :
– the picture and the title
– the title and the excerpt
– the excerpt and the next picture

2) Is there any possibility to keep the html markers in the excerpt ? Such as break lines for example ?

Thanks you