Yep, the issue with that approach is that - but hopefully it will be fixed in 7.16 or later (it has been given as solved in one of the latest 7.15 but seemingly it doesn’t actually work) is that the DNS (and consequently also the NTP) don’t work in a VRF.
A few posts later, in post #37, I posted a configuration with the VRF “reversed” to allow these services to work (which is the one I am actually using) .
About connecting to the original router, of course it is not possible without some special setting as it has the same 192.168.1.1 address as the Mikrotik, and from the LAN side the “first” 192.168.1.1 encountered is the Mikrotik.
Very likely it is possible to use another IP and “re-map” it to the original ISP router IP, using dst-nat or some other trick, there are some hints here:
http://forum.mikrotik.com/t/double-destination-nat/175277/1
and in connected thread:
http://forum.mikrotik.com/t/managing-two-separate-subnet-with-same-class-addresses/130530/1
I never delved deeper in that particular aspect because I have no reason to connect to the ISP router (as all I can get is a prompt for user and password credentials which I don’t have).