It is Cisco's accepted practice to take a network and subnet it using a 30 bit
mask.  This will leave you lots of networks with two usable host addresses.
This way you're not wasting IP addresses as badly.

Your second question is a subnetting question.  Yes you can advertise a route
to a whole network to the rest of the world while behind the router the network
is subnetted.  This is actually preferred and most routers will consolidate
routing tables to keep routing table sizes down.  

The biggest thing that scares me here is the quality of your instructor! :-)
But your employers have decided to subscribe to the Microsoft Money Making 
Machine.  This is actually one case where you don't get what you pay for, you
get less.

	Mike Neuliep