Securing LFNC conduit to joists
LFNC is not pretty but it's easy to install.  You have to strap it every three feet and within one foot of the boxes.  You can't exceed 360 degrees of accumulated bend between boxes.  Since it's impossible to get the stuff really straight, and it's sticky inside, you're better off limiting it to 270 degrees of bend between boxes.
The straps made for rigid metallic conduit or PVC conduit should fit well enough, and two hole straps will work well enough where running perpendicular to the joists.  Parallel to the joists, straps probably won't fit along the bottom of the joist, but you can just strap the conduit to the face of the joist instead of the bottom edge.
If you use reasonably small screws, like #10 or smaller, splitting the joist is unlikely, but it never hurts to drill pilot holes.
Use gray surface mount type plastic junction boxes and drill right through the back of the boxes to secure them to the joist.  You could use two of the four mounting tabs on the box but they'll tend to snap right off.