1) For the heading I added this css:
#certificate .certificate .certificate_content h1 span {
font-size: 27pt !important;
color: #ff0000;
}
In this css you can change the font-size and the colo code according to your requirements.
2) There is no second background image, the first image is repeating that's why you are seeing this repeated image.
I added this custom css to avoid the repetition of the background image:
#certificate .certificate .certificate_content {
background-repeat: no-repeat !important;
}