2.) This is because you are using the gap element with 50 pixel height. You may insert another gap with a smaller height with at least 15 pixel height. You can then hide/show the gaps using the “Hide During Break Points” options. For more details about this option, please check this out: https://theme.co/apex/forum/t/hide-during-breakpoint-explained/17378
3.) This is because you have inserted this:
<span><small>Our Partners</small>Thanks for the<strong class="support-color-change"> Support</strong></span>
If you remove the <small></small> tag, your issue will be resolved.
4.) This is because this is a hidden gap element that is only visible in smaller screens.
Just a tip for you to easily check your page while editing in Cornerstone. You can always use the skeleton mode when editing for faster response and easy access of all the elements in the preview area. This is also helpful especially if one of the sections or elements is not visible or hidden in selected screen size or you may have applied visibility options to a section of element.
5.) Your subscription form is displaying in smaller screens.