1.In fact I am not quite sure about what you mean for the first question. I am running the rtpengine daemon downloaded from github, sip wise/rtpengine.
   What does 'dpkg -l | grep rtp' show?
 
2.There is nothing prompt on command cat /proc/rtpengine/0/list. The file is 0 bytes and empty.
  That means your streams are not kernelized and all the traffic passes through user space. I have never run rtpengine software on a virtual machine so I don't know if it should kernelize the streams in this case; you could try it. On real hardware, it should. Thus you should get rid of those errors.
   Check point '1.' and make sure that you have the necessary packages needed for kernelizing the streams referred in [1] (i.e. ngcp-rtpengine-kernel-dkms, ngcp-rtpengine-iptables) along with the rtpengine daemon (ngcp-rtpengine-daemon); those should be the minimum packages needed. Grep the README for "in-kernel" keyword for more info.
 
3.Our kamailio is using loose route.
  I was asking about "strict source" form README [1]. Nothing related to kamailio's 'lr=' parameter (if that is what you meant). However your problem is at point 2.

Regards,
Stefan Mititelu

[1] https://github.com/sipwise/rtpengine