I have Mylar on the floor too, so I guess spraying the mylar is the best bet.
When I bought the lady bugs they came in a pint container the shape of an pint of ice cream with a little hole cut in the top and a piece of screen over the hole. They came as lady bugs though, not eggs. And there were no eggs in the container. So I'm not sure what you mean about the eggs.
If you're cool tube has a lip for the duct to attatch onto, and if you have flexible duct, then you don't have to replace the duct. Just buy two 3" clamps, open both of them, and fit them together like one big clamp. Putting the two clamps together will let you tighten it enough to squeeze the 6" duct onto a 5" lip. I had the same problem with my portable AC lines, the're 4.75" and there's no duct made to that size. And I couldn't find a 5" duct, so I used 6" duct and figured out that trick with the clamps to make it work. Plus it's a little easier to push air through a 6" duct than a 5" duct.
You can avoid bleaching by using a light mover or increasing the dark period and shortening the light perioc. I think 16/8 is as much dark as you can give them during veg.
In my room I needed an A/C because of the hi level of heat caused by some very cheap hoods. If I new then what I know now, I would have bought one 1,000w light with a good hood instead of three 400w lights with cheap hoods. I bought a portable A/C because I use an inside closet. The portable A/C has two ducts coming off of it, one for intake and one for exhaust. So this is what I use for exhaust. I don't have any way to run a 2nd exhaust or intake. There just isn't enough room.
I do have 2 fans in the room though. An oscillating fan that blows on the plants, and a floor fan that's in front of the portable A/C pointing straight up to blow the cold air up. There's no way to change where the exhausts takes air from though.