Yes, there are add on cards for adding more SATA ports to your computer. They start at around $30 and go on up. You can also get a RAID card and just use it for running drives. I've included 2 links, one is for PCI cards and the other is for PCI-e cards. If your motherboard has any PCI-e 1x slots then that is the way to go because the PCI-e will run faster and smoother than the older PCI slots.
As for booting off of a CD-ROM/DVD drive attached to SATA card, that can be done but can be more trouble than it's worth. I would recommend that you switch some of your hard drives to the SATA card then plug DVD burner in to the motherboard.
I've also got a used 6 port (4 internal, 2 external) SATA card (PCI) I can sell you if you are interested. Send me a PM
Here are the links for the PCI and PCI-e cards. I am using newegg.com as an example, because I do a lot of buisiness with them, but any large online PC hardware will have these cards. You can google search 'SATA card' or 'SATA RAID card' and you will find many retailers
http://www.newegg.com/Product/Produ...010073 1187129175&name=PCI to SATA / IDE Card
http://www.newegg.com/Product/Produ...0073 1187117620&name=PCI Express to SATA Card