Hello Khan,
there is an EIGRP interface command that allows to keep the original next hop in routes: it is used together with
int tunnel 100
no ip split-horizon eigrp as-number
no ip next-hop-self eigrp autonomous-system-number
typical usage is in DMVPN using EIGRP on the multipoint GRE virtual flat network on the hub(s) routers.
Without the no ip next-hop-self eigrp autonomous-system-number spoke routers see routes of other spokes with a next-hop = hub router address and this doesn't allow the setup of a dynamic spoke to spoke ipsec tunnel.
Disabling split-horizon is needed to make the hub router able to send updates out the same interface it has learned them.(distance vector aspect of EIGRP)
b) offset-list
if you provide an offset of 0 you are doing nothing.
An offset-list uses an acl to specify over what routes (if present) to apply its metric change action
the acl is a required parameter note the curly brackets { this means mandatory parameter
offset-list {access-list-number | access-list-name} {in | out} offset [interface-type interface-number]
[optional parameter] is to specify an interface
see
http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_eig2.html#wp1012264
Hope to help
Giuseppe