OK, just finished my first plane (Hangar 9 Value Series Cessna) and I am concerned that there is nothing holding in the foam padding where the receiver and battery are. The foam padding seems to be very loose and moves around the compartment quite easily. Any ideas to help would be greatly appreciated! Thanks in advance!

You need to do something to hold the battery and rx in place. If the battery is in the tank compartment that is usually good enough with some HD foam. The rx as you say is often loose in the fuz under the wing, can you get a couple of cable ties around something to hold it in place or glue in a couple of blocks with open screw in eyes and use a couple of light elastic bands to hold the rx down.

If the battery is in the same open open compartment you MUST take steps to make sure it does not move around with either bands or ties.

Sometimes it's not easy and the results can be ugly. I glue in scrap pieces of balsa where needed. This is how I did it on my Four Star 40.

The manual directs:
"Use radio packing foam (available at your local hobby dealer) when you install the receiver and battery. With a sharp hobby knife, cut a solid layer of foam the size of the compartment that is in front of the servo tray. Cut out another layer of foam that is identical in size, however, cut an opening in the center of this foam so it will accept the receiver battery pack. Place another solid layer of foam on top of this layer. Cut another layer of foam to accept the receiver. The final layer of foam should be solid."

That seems to be fine to prevent the battery and Rx from sliding around the compartment.
However, I see two problems:
1) Nothing prevents the assembly from moving vertically.
2) There is no freedom to relocate the battery forward or rearward in order to adjust the CG; hence, additional weight needs to be added for balancing.

What I do:
1) Wrap each element individually with foam and rubber bands.
2) Pre-balance the model by moving the battery back or forth.
3) Once the rough location is determined, screw some Velcro strip to the fuselage in a position that keeps the battery from moving under the strong forces of future hard landings, flip over’s, etc. (Some pieces of wood may be necessary, but try making them easily removable rather than glued).
4) Do the same for holding the Rx, but consider placing it out of the way of the battery in case of a crash (on top or behind the battery).
5) Verify that wires are not under stress by being too tight or by vibration from the engine (use some foam to prevent wire movement or oscillation, especially at the points where they enter or leave the battery and Rx and at male-female connectors).

Have look in the 3d forum great planes 160 biplane,look through the slide show there are some good pictures that show radio installs.

Thanks for the ideas - really appreciated. I knew that it would not be good to have the battery and rx able to move around so easily. Will work on a fix...

It's a good idea to locate the battery somewhere in front of the receiver in case of abrupt stops. If the battery is behind the receiver it could crush it in a crash. Just a simple thing I do.

Here is a trick. The primary goal is vibration damping, secondary impact resistance.
Remember the old egg drop in a protective container science class experiment? Well this is a good way to mount and protect the expensive reciever. The softer the foam the better and DO NOT OVER COMPRESS THE FOAM when mounting. Stiff or compressed foam will transfer vibration and shock and won't be helpfull. I use recycled electronic (computer ) shipping foam. Its free just call around.

Cut a block of foam as wide as the fuselage and as long as will fit in between other gear. notch out for switches etc. Slice down the middle 1/2 to 2/3 through the foam block. Carve out a pocket for the RX. Insert the Rx with all servo and battery plugged in. Insert the block.
Your done. It will survive a full power face plant.

Another method is wrap as previously shown and glue a velcro strap to the floor of the fuse. Wrap velcro around the foam/rx package (not to tightly). Easy to remove as needed.