Hi,
I've labbed this in GNS3 and I think I understand why it is displaying the "dst" as it's own private IP address.
When I tested it, I can also see that on SITE1 router the "dst" is it's own private IP address. I believe this is because the SITE2 router initiated the VPN (by sending interesting traffic). To prove this I cleared the VPN tunnels' and initiated traffic again but this time sourced from the SITE1 router, once the VPN was established I could see the output on the SITE2 router confirmed the "dst" was it's own (site2's) private IP. My assumption is that this is probably by design.
In regard to your other issue, are you experiencing this issue just in packet tracer or in a real life scenario, but you are attempting to replicate the issue in packet tracer?
You may want to increase the Security Association lifetime (e.g 86400 seconds) and use stronger encryption, hashing and dh group. The SA's won't renew every 1800 seconds as you currently have but if you use stronger algorithms that should be ok.
crypto map ftthmap 10 ipsec-isakmp
set security-association lifetime seconds 86400
crypto isakmp policy 5
encr aes
hash sha
group 15
Other than that, there doesn't especially look like a major issue with the VPN config.
HTH
