Mounting lights - drop ceiling

you need to mount the lights safely which would be the wood above the drop down.... The drop down ceilings do not support a lot of weight.

it depends on what fixture you need to hang. If it's around 1 lbs you can do something magnetic. Otherwise you'll need to secure to something above the tile which can be messy, and some venues don't allow.

Most venues that have drop ceilings will NOT permit moving or removing the ceiling panels due to fire code violations.

If you are granted permission to remove the ceiling panels, I strongly recommend fastening to structural steel and not the aluminum ceiling grid pieces.

I would NOT want to assume that civil liability on my own...too many disasters in clubs where someone tried to cut corners, etc.

Just my two cents...

EDIT TO ADD...

I reread your original post. I agree that fastening to the wooden truss above the drop ceiling would be adequate, ASSUMING you can make your local fire marshal happy with the integrity of the drop ceiling. Fire marshals take a dim view of punching or cutting holes in the ceiling tile. There should be NO gap between your metal hanger and the ceiling tile...they should touch.

think of it this way, if you wouldnt trust the stucture to hold the light up above your infant kids head...then it isnt safe always always put safety first when it comes to hanging lights...if riggin is involved you should consult a rigging expert to help you. When i went through rigging school i was told, "if it looks like redneck rigging, it will kill someone" might get away with it this time, but one day it will catch up to you. Always best to just do it right every time and keep everyone safe :-)