Doctype should be on each page - and IMO meta data can also be repeated - I have all that within a template usually and so it gets repeated, although the homepage is I reckon the most important for all that - it should be the first page to get spidered. If you happen to use frames, make sure all your data is in its frames page head area.
A starter page from Dreamweaver gives this .......
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Untitled Document</title>
</head>
<body>
</body>
</html>
Make sure no space left above the doctype page code start, unless adding in some php initially or a cgi call, but still no white space. Your meta data can include content, keywords, author - numerous options but, keep a keywords list IMO 32 items max - search engines will reject ultra long strings of keywords.
