Upfront/Spirit - Default Settings for Categories/Blog Posts

I'm having some trouble with the Spirit theme on Upfront. When I create a new blog post, you can go into the post on upfront to make small changes. Examples might be changing the title at the top (over the featured image) to something else from "Blog", deleting the comments box, etc.. However, these changes occur on a post by post basis, even when I select 'apply to all posts of this type'.

I'd really like to remove the word "Blog" from my blog posts (it sits on top of the featured image). In an ideal word, I'd like this to default to the blog post title because the text is in H1 and, though I'm not an SEO expert, I understand that H1 text is important for search engines.

Right now this has to be done manually on each post. Is there a better way?

Also, how can I delete the comments form on the bottom of the page? I have to do this on a post by post basis right now.

Another related question: is there a way to change the default banner image for my site. When I've forgotten to change a category's image, I get a black and white pixelated image at the top of the page (with the word blog transposed over it - see screen shot). Is there a way to change this so that I can choose the default image?

Finally, I am having a major issue with the featured image. Obviously, large high resolution images look great in the blog posts and on the main page. But they look terrible when they are listed on the categories page or search. Take this example where you click on my username: https://angrytiger.com/author/ryanruppert/

The large image stretches vertically downwards to a ridiculous size. The identical image looks great on my homepage: https://angrytiger.com/

Is there a way to fix that?

I appreciate your help with all of these issues.