Ok, the picture you submitted is almost right. the bottom choke is reversed. the spanset should come up the outside of the bottom rail instead of, as pictured, the inside. The safety steel should be run between the top and bottom rails and attached to the hook with a shackle where the spansets attach. The spansets I mentioned earlier with the cable core are shorter, and can be rigged using the top rails.
Also, you asked about safety chains/cables. Industry standard is usually one safety per instrument. An instrument/fixture can be a single unit, but a bar of 6 pars is also considered one instrument. I however, like to be a bit more cautious, and use one safety for every clamp. I don't care how small the fixture is, if it falls from above, it will hurt when it hits your head.
A point about rigging. (no pun intended) If you are going to be hanging things, or rigging, over peoples heads, you should have some type of training. Currently there is no certification for entertainment riggers. ESTA is working on a program to do just that, which will make it a bit easier to get insurance. There are several publications available on rigging, and I believe in August there will be some kind of rigging workshop in Vegas.
If you choose to rig without insurance (not at all advised), make sure you rig properly. if there is an accident, you're in a much better position if you've done everything by the numbers.
I would advise in the future to hire an up-rigger through an insured local production company. (you can do the down yourself) not cheap, but worth every cent.
Hope this helped.