New fibre install with a Cisco 2801 router. What else do I need?

Hi,
I currently have a setup with a Belkin F5D9630 DSL router feeding directly into 2 x Netgear GS724T which gives about 30 computers access. All the DHCP management is done by the Belkin F5D9630. I know this is not a great way to do this, which is why im looking for advice!
I also have a Windows server that deals with a RAID array as our central storage, but this also just gets an IP from the same place as everything else.
So when I get the 50mb fibre installed with the Cisco 2801 router;
– What should ideally use for IP management?
– Do I need a hardware firewall, or is the one in the 2801 enough?
– How should I add WiFi into this?

Many thanks,
Tom.