#14 is very vague and it really depends on what you are trying to accomplish. If you just wanted to failover the two T-1's you could just use floating static routes. However, if you wanted to load share based on interface metrics across both T-1's you would use BGP. There really are 2 right answers.

Also, I find it kind of funny that an ISP would have 2 T-1's to the Internet, and then have 4 clients with T-1's coming into their network. Anybody that knows anything about networking knows that this is a recipe for disaster because you have a potential for about 6Mbps of traffic coming in from your clients, but are only able to provide them with a maximum of approx 3Mbps of throughput to the Internet.