OT:NAT-Transparency Aware DMVPN

Dear Experts,

I was going through DMVPN configuration Guide on Cisco's website:

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t13/feature/guide/ftgreips.html

And would like your help in understanding two things or getting references
if possible:
1)Apart from having a lower overhead (transport mode) by not adding a new
src/dest IP addresses of the endpoints, why is transport mode preferred over
tunnel mode in DMVPN?

2)NAT-Transparency Aware DMVPN: I have a problem understanding this, please
correct me if possible or if you have a better understanding please help
A)When A spoke is behind a NAT/PAT Device, NAT-D can take place as in
regular IPSec and by sending the hashes of the IP addresses the endpoints
can tell if a NAT device exists. However NHRP's role is to map the Spoke
Tunnel IP address used to the Physical "real IP address". Does NHRP
registration in this case happen with the Natted IP address and thus the
virtual address is mapped to the Public Natted IP address?Are we only
referencing static one to one NAT scenarios between the endpoint RFC 1918
address and the Public Natted IP address?

Thanks for Any Help:)

-- 
KJ
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