Wasn't that a song?

Now that I have my hot engine problem isolated to the thermostat choice I had originally made and it's running cool again...the housing is leaking slightly- I come back 8 hours later and there's a drop on the bottom side.  The one I have is original and I was wondering if I'd be better off getting a new one from Mummert so I figured I'd ask.  

For starters- on the original one- is it possible to over-tighten it?  Will it eventually crack if I reef down?
Second- Are the truck and car thermostat housings identical OTHER than the orientation of the neck?  Bolt holes will line up correctly, right?  I was thinking of using the truck one for aesthetics.  
Third- Looks like Mummert's are aluminum.  Any concerns there as far as getting it good and tight- could I mess up and crack it?  There's no photo of the bottom side online- It doesn't use an O right seal or anything idiot proof like that, does it?  
Lastly- is there an easy way that I'm missing to keep a vertically mounted thermostat housing in place while everything gets tightened down?  One of Ford's better ideas...that wasn't, if you ask me!  

Thanks again.