1- Have you tried using Main Options > Post Specifics > Featured Images settings?
If for some reason you cant use these because you need different settings elsewhere, you can use the rules below in Main Options > Fonts & Custom > Custom CSS Rule box.
.atw-show-posts .post {text-align:center;}
.atwk-slide .post img.fi-alignleft, .atwk-slide .post img.fi-alignleft-pb, img.fi-alignleft, img.fi-alignleft-pb {margin-right:0px;}
2- You should be able to do that by doing the following.
Select to display post with excerpts in the filter.
Then add the rules below in The custom CSS Rule box
.atw-show-posts .entry-summary {display:none;}
.atw-show-posts .post:hover .entry-summary {display:block;}
If it does not work, you need to post back with the excerpts visible