Eazy Image Slider Block

Yes, currently only via CSS. The selectors for the buttons are:

.eazy-image-slider .tns-nav button

and for the active state:

.eazy-image-slider .tns-nav button.tns-nav-active

Example you can put in your themes style.css:

.eazy-image-slider .tns-nav button {
    background-color: #fcc;
}
.eazy-image-slider .tns-nav button.tns-nav-active {
    background-color: #e22;
}

Yes, same applies as for the dots, currently only via CSS.

.eazy-image-slider .tns-controls button:before

and for the hover state:

.eazy-image-slider .tns-controls button:hover:before

Example you can put in your themes style.css:

.eazy-image-slider .tns-controls button:before {
    background-color: #fcc;
}
.eazy-image-slider .tns-controls button:hover:before {
    background-color: #e22;
}

Yes, to do so, simply add following lines to your themes functions.php:

For the styles:

function eazyimageslider_remove_style() {
    wp_dequeue_style( 'eazy-image-slider-style' );
}
add_action( 'wp_enqueue_scripts', 'eazyimageslider_remove_style', 99 );

For the script:

function eazyimageslider_remove_script() {
    wp_dequeue_script( 'eazy-image-slider-view-script' );
}
add_action( 'wp_enqueue_scripts', 'eazyimageslider_remove_script', 99 );

VH is a unit relative to the viewport. Which means if you set your slides height to be restricted to 50vh, the slides will have the height of 50% of the viewport.