Title fonts and page size

1) I can’t really say wihout looking at your code (header.php – feel free to put it in a pastebin if you want and I’ll take a look), as I don’t know what functions are called from it.

2) You need to add something to (or update it if it already exists) your style.css file –

#header{
    1.4em; // Adjust size accordingly
}