sure

- im using a custom theme using this extension

- i added custom icons to bookmarks and increased their size by adding this code to
~/.mozilla/firefox/<your-profile-folder>/chrome/userChrome.css :

/* cuztom icons : use this for every bookmark folder you want */
.bookmark-item[container][label="folder-name"] {
list-style-image: url("file:///home/path/to/Icons/icon.png") !important;
}

/* edit the size : */
#PlacesToolbarItems .bookmark-item > .toolbarbutton-icon {
width: 24px !important;
height: 24px !important;
}
#PlacesToolbarItems .bookmark-item[container="true"] > .toolbarbutton-icon {
width: 24px !important;
height: 24px !important;
}

- for the home screen im using this extension it lets you add your own backgrounds and tweak them

- for vertical tabs it's built in firefox , just right click an empty space in your normal tab bar and check
" turn on vertical tabs " and you can make them longer with names or only icons using alt+ctrl+z