I don't know of "Visio add-on" however, there are lots of Visio stencils of Cisco devices available to download here:http://www.cisco.com/en/US/products/prod_visio_icon_list.htmlThese are really useful for impressing the management with fancy network...
In the dhcp config the network should match the LAN subnetUse the command ip dhcp excluded-address to limit addresses from the scope.To make sure the DHCP service is running. use: service dhcp command
The network in your DHCP config doesn't match your LANip dhcp pool bloomington network 192.168.2.128 255.255.255.192interface FastEthernet0ip address 192.168.2.1 255.255.255.0Try the following instead:ip dhcp pool bloomington network 192.168.2.0 25...
3750 switches do not have a hardware clock so cannot be configured to be NTP Master. In similar situations I have connected an otherwise disused Cisco Router which does have such capabilities.