PDFMaker uses the mpdf library so you'll find a definitive answer at http://www.mpdf1.com/mpdf/index.php or https://discussions.vtiger.com/index.php?p=/discussion/53074/pdf-maker-own-font/p1
I've styled my pdfs with a css file referenced from each pdf template. If you can do it this will be the way.
Yes. Just you have to download the zip from http://www.neevtech.com/vtigerpage/ and extract.
After that you will can select this new theme from user preferences.