Yikes... a good book alone is probably not going to do it, but perhaps a Learn Linux in 24 hours will do the trick. Probably the most cost effective way to get started is by renting a VPS instance of Linux so that you can do whatever you want to it and then throw it away when you are done without committing to a complete box.
Personally, I do not host DNS or Mail any longer - I let my hosts do that - I focus solely on LAMP style boxes that are all behind a firewall. I VPN into them so that I can talk FTP, SSH etc to them, but only port 80 and 443 are allowed through the firewall into the boxes. Having gotten hacked nasty several years ago, I find that this sort of arrangement offers me the best sleep

Post here with your qqs as you go forward... I was a Mac and Windows guy with zero *nix experience about 6 years ago so I understand the conversion headaches.
/p