You would need to install kernel module in host machine, only then it will be available in docker container. You will also need to mark container as privileged container and enable 1-to-1 NAT for RTP port range between host and vm (i recommend using iptables for this instead of using docker port expose feature).
Regarding RTPE compilation, yes it is quite difficult on Ubuntu 18.04. You have to tweak <git-repo>/debian/control file and manually add compat file. Also there are various dependencies that are not listed in wiki and cause problem in installation of deb packages, which you can install later on after reading the error messages.
As for install order, for me "dpkg -i *.deb" works fine and i control which features to use and which not from config file. Otherwise just install whatever seems appropriate to you, don't worry dpkg will install other ngcp-* packages as needed.
Hope this helps.