I have the same one. Def +1 to the preheat... I also put a blanket on top of mine during the mash to try to help a little bit more.
I used aquarium silicone and some SS washers. here's the silicone: http://www.dap.com/product_details.a...67&SubcatID=27
No issues with taste that I noticed. Says it's food safe. I wanted to make sure to coat the foam in the hole for the spigot so it wouldn't get exposed to wort then start to form mold.
So far I've only done three batches over about 4 months so I can't say anything about it holding up over a long time. The sealant was like $6 or $7 i think and I have a lot left over (probally enough to re-do it another 3 or 4+ times) so if i need to reseal I can.