Hi,

1 & 2/ This theme supports 3 ways to setup a homepage - and you're using way 2: Customizer. Check more on documentation for Soledad theme here

If you want to keep use Customize to config the homepage, you can add more this code to Customize > Custom CSS to adjust the width of sidebar:

@media only screen and (min-width: 1170px){
.penci-sidebar-content{ width: 25%; }
.penci-single-style-10 .penci-single-s10-content, .container.penci_sidebar #main{ width: 75%; }
}

Change values 25 and 75 on the above code to values as you want.

Make sure total of this 2 values is 100. Example:  27 and 73.

For adjust the space between slider & below, you can add more this code to Customize > Custom CSS:

.featured-area{ margin-bottom: 30px; }

Change value 30 to value as you want.

3/ Unfortunately, currently the theme doesn't support showing comment there. We have a plan to update this feature in the next updates version of Soledad, please wait for the new update to get it.

Best Regards,

PenciDesign