Hi Sergio,

for both of those task, you need to use Custom CSS:

1. To remove icon

.sp-vertical-middle .floox-icon.floox-picture {
  display: none; visibility: hidden;}

2. To change Hover Layer bg color from Blue to Transparent Dark Grey

.sp-simpleportfolio.sp-simpleportfolio-view-items .sp-simpleportfolio-items .sp-simpleportfolio-item .sp-simpleportfolio-overlay
{background-image: none;}

You can also make that dark layer even brighter using also that line

.sp-simpleportfolio .sp-simpleportfolio-item .sp-simpleportfolio-overlay-wrapper .sp-simpleportfolio-overlay 
{background: rgba(0,0,0,0.1);}