Support and Info required for setting up DHCP in my environment

Hi! I was hoping you could shed some light on my DHCP concern. I intend to implement DHCP in my environment and I need to clarify some things first before I actually do it. I want to know if I need to put public DNS at the forwarder; if it is possible for me to give certain users a static IP; how much lease I should implement; and what are the problems I am likely to encounter when implementing DHCP. Currently, some of the static IPs are not working that I need to change the IP address because only then can users access the server applications. Am I bound to encounter the same problem when I install DHCP? I hope you could give me some advice. Thank you.
