All of the edit page changes are CSS tweaks that you can override by editing the MediaWiki:Common.css file for your wiki. The following is the CSS that was added with these changes:

#siteNotice,
#siteSub,
#contentSub,
#mw-anon-edit-warning,
.mw-newarticletext,
.previewnote,
#user_masthead,
.usermessage {
	display: none !important;
}

.firstHeading {
	border-bottom: none;
	font-size: 14px;
	font-weight: bold;
}

#editingTipsToggleDiv {
	margin: 0 !important;
}

#new_edit_page_preview_notice {
	background-color: #c00;
	color: #fff;
	margin: -8px -8px 2px -8px;
	padding: 8px;
	text-align: center;
	font-weight: bold;
	font-size: 1.1em;
}

#new_edit_page_preview_title {
	clear: both;
}

If you would like to add all of the information that was removed from the page, such as the sitenotice, newarticletext, etc., you can just add the following text to the bottom of MediaWiki:common.css:

#siteNotice,
#siteSub,
#contentSub,
#mw-anon-edit-warning,
.mw-newarticletext,
.previewnote,
#user_masthead,
.usermessage {
	display: block !important;
}

If you need additional help, please contact a staff member and we'll be happy to help.