On another note, could you explain what 'no ip source-route' refers to? Is the above to prevent routing loops, routing updates can not send back to port that update was received from?

Here are some commands that you might want to enter to increase the security and usability of your devices.

no service pad

no service config

no service finger

no ip icmp redirect

no ip bootp server

no ip identd

no ip finger

no ip gratuitous-arps

no ip source-route

service sequence-numbers

service tcp-keepalives-in

service tcp-keepalives-out

no service udp-small-servers

no service tcp-small-servers

service timestamps debug datetime localtime show-timezone

service timestamps log datetime localtime show-timezone

service password-encryption

What does ip gratuitous-arps refer to?

A Cisco router will send out a gratuitous ARP message when a client connects and negotiates an address over a PPP connection. This transmission occurs even when the client receives the address from a local address pool. By default it's off, but we like to make sure by entering the command.

ARP request is a broadcast to local hosts by the router, seeking the MAC address of a host with known IP address. So, when the ARP request goes through a PtP, the action is refered as a gratuitous ARP, Yes?

Actually the router sends ARPs on behalf of the device.