Hello Saša Matić
Please use this JavaScript to Template Options -> Custom Code -> Custom JavaScript
jQuery(function($) {
$(document).on("click", ".menu-deeper", function(event) {
if (event.target.classList.contains('menu-toggler')) return;
if (event.target.children.length) {
event.preventDefault();
event.stopPropagation();
$(this)
.toggleClass("menu-parent-open")
.find(">.menu-child")
.slideToggle(400);
}
});
});
Then you can click offcanvas menu item title to open the sub-menu items.
Your second query might or might not be possible to do. Please consult a developer for this. Sorry, we do not provide customization support.
Best regards