Simple banner code

This is some simple code to display a div with content which changes:

function SCRATCHhello(Content){
   console.log("Hello");
   var D = document.querySelector(".SPLASHbanner");
   D.innerHTML = Content;
}

var SCRATCHquotes=
['Iguana changed my life',
 'Iguana makes work more efficient',
  'I love Iguana'];

function SCRATCHquote(i){
   i= i %SCRATCHquotes.length;
   SCRATCHhello(SCRATCHquotes[i])
}

var SCRATCHindex=0;
setInterval(function(){
   SCRATCHindex=SCRATCHindex+1;
    SCRATCHquote(SCRATCHindex);
}, 3000);

How can change the interval to 5 seconds?

How can make it convenient to write longer quotes?

How could we add formatting to the quotes?

How could we style the div?