Hi Natasha,
I hope you are well today and thank you for your questions.
1. Justify the text in the excerpt. Especially on mobile phones the white space is too much.
Could you please share the screenshot of it?
2. Remove the Category: title. Would still like the category title to show but without the word Category.
You can try achieving this by using the custom code solution posted in the following topic.
https://colorlibsupport.com/t/remove-blog-post-entry-details-in-blog-page/#post-66759
3. Reduce the white space below the featured image and between title and content- if it will not spoil the beautiful responsiveness that it has currently.
You can try achieving this by adding the following CSS code in the Custom CSS option of your theme on the below path.
Admin Area -> Appearance -> Customize -> Additional CSS
#page .post-inner-content {
padding-top: 15px;
}
Best Regards,
Movin