Hi @Astrobobo,

I hope you are well today and thank you for your questions.

Is it possible to make the standard gallery centered and standard wdth?

You can change its width by setting content width by using the following solutions.

https://jetpack.com/support/tiled-galleries/

https://wordpress.org/plugins/custom-content-width/

Also, is it possible not to show the featured image on top of the page or post?

You can achieve it by adding the following CSS code in the Custom CSS code option of your theme on the below path.

Admin Area -> Appearance -> Theme Settings -> Custom Code -> CSS Code

.single-post .post-meta-thumb,
.page .post-meta-thumb {
display: none;
}

Best regards,
Shufflehound team