People here typically use 'Great Stuff', 'Handi-foam', or 'Touch n foam'
they are just foam insulation products that come in a can. You can get them at any hardware store. I like the black 'Touch n foam' that is supposed to be for ponds.
The silicone is typically GE or DAP... just make sure it is 100% silicone. Everyone usually uses black or brown, as it makes missed spots not look so bad
Really though, you have 3 posts up that are all easily answered if you did a few searches... I find it helps just to check out some people's construction journals and such...
First and foremost though, since you are new (Welcome to the board btw!) I recommend you read ALL of these, especially the search function one... http://www.dendroboard.com/phpBB2/viewtopic.php?t=16075
it will make your life and everyone elses a little easier.
forgot to mention... check out some of the sponsor's websites... many of them have little DIY guides to building tanks that are also very useful (Saurian.net is very helpful) I used a combination of those and the journals from this site to get myself started