There was no purpose or reason for the /24 mask. You are correct, the /30 is preferred for peering connections.
If those two switchports are part of a Layer 3 port-channel, the "ip access-group" command will be under the Layer 3 port-channel interface.
yea, you are sort of right. Configuring EIGRP isn't really difficult, but its a whole different animal compared to RIP
@HazemHead for labbing purposes there is not much of a difference