White solid drain pipe vs black flexible corrugated pipe for a french drain
Tim Carter at AskTheBuilder.com has a lot of articles on French/Trench drains. He likes solid pipe and I agree. You are correct in that the holes point DOWN. Here's why - the water won't magicially find the holes if they are pointed up, but if they are down, the water can fill the trench and then flow into the pipe. Put a cleanout on the upper end if you can, if you don't want it sticking out of the ground, then come up with a 45 elbow and bury the cap right below the ground. I would NOT put a sock on the pipe. That will just clog. If dirt gets into the pipe, most will flow out because its rigid, and hopefully you can put a cleanout on it, or you can run a snake in from the outlet. I would put some straw or landscape fabric right under the top soil. Use 3/4 gravel as filler, not smaller. Read Tim's articles if you get a chance.