I have the Janome 3160 QDC machine for traveling. It weighs 12 lbs and has all your requirements except the knee lift. Comes with a lot of accessories - hard cover case, feet etc. It is a great little machine and I traded my basic Janome Gem Gold for it as it had more features than the Gem. Several of my quilting friends have this machine and we all love it.
I searched out a traveling machine by the same manufacturer as my "home" machine because the feet and bobbins were interchangeable. Not sure of all brands but worth thinking about as you make your choice.
Good luck in your search.