Ken is right, we can't help you much without seeing your site, so do provide the URL to your site.
Also, those error messages are important to give us an idea of what went wrong and how we can fix it, and how we can prevent it in the future. If you see any more error messages in the future and don't know what it means, post about it here in this forum and we can take a look. If this is a live site and you don't want to mess it up, set up a development site and do all your development and experimentation over there.
As for the slider, I suggested that you use the "Background image and excerpt" option so that the image fills up the entire slider, so there's no unused extra whitespace there and there's no need to center the image as well. It will add the excerpt, button, and link to the post, but all of these can easily be removed via CSS.
No answer, no donate.
Come on, this is a community forum, not enterprise support. If we only help people for the donation, trust me when I say that only a handful will receive help. Donation is just that - donations. We don't set any precedent or any obligation on you to donate, and that's not how things work in a community forum. You can't "buy" our help with donations, cause that violates the open-source community spirit that forums such as this live by.