1) It just rained here in Souther California for 3 days. I put 300 miles on my car in those three days (running and building materials for about 5 ADTR projects.) I have also had this intake on my car for well over a year. I have never ever had water in the filter or anywhere near it.
2) The filter is supported by silicon that is meant for turbos so it is super tough and can withstand 700 degress F. I dont think the guys on eBay use that in any way, shape, or form. Also the guys on eBay dont give you the choice of IAT location, we do and because we do them all by hand, we can do that. But we will have a heat sheild box later and the intake will be sealed inside and supported even more.
3) When you install the filter, I recommend just disconnect the battery for like 10 min, then reconnect and that will reset the computer and the computer will relearn with the new intake. The computer will basically adjust to your mods. The people who have rough idles usually have dirty Throttle Bodies, or have done something wrong or actually just attach a K&N to the accordian tubing which is alot of turbulance.
Actually our intake is $145 shipped to your door.
Hope that answer all your questions. If you have anymore you can reach me with the email address below.