She has such a contented look at the end If you want to see the full width of the video on youtube the url is (it seems to be cut in half in the forum post - at least on my computer screen).
Cornmeal is supposed to be good for getting rid of ants (leave some out, they eat it, and then it swells inside their digestive organs). Also, if you know where their nest is pouring boiling water into it should help get rid of them.
It looks like what is known as 'meat spots' which are bits of tissue from the wall of the oviduct - it is a bit icky to think about but they are quite harmless to eat (or you can just remove them).
If you enjoy planning and building things then building your own coop can be a really fun project and would probably save you a few hundred dollars (particularly if you can find sources of recycled free/cheap materials). If spending the extra dollars isn't an issue and you wouldn't get a kick...
If it isn't down to broodiness then another possibility may be that you have an egg thief - predators obviously will take them if they get the chance, and I have even heard of pet dogs carefully moving eggs from one place to another (for reasons best known to themselves!)
If it is to be used basically 'as is' I think the top floor will be cramped for four chickens when closed up as it would not give them much space to turn/move around in.
Predators won't always warn you when they are in the area so even if you don't see them it is probably best to assume that you have a variety of four-legged and winged predators close by.
The minimum for adult chickens (depending on breed size) is 1.5 - 3 square feet of floor space inside the coop house
http://www.ca.uky.edu/smallflocks/Factsheets/Poultry_management_specifications.pdf
although it is obviously more comfortable for them if you can provide more than the minimum.