1, Yes I have seen them blown completely off the wall and send fragmented pieces through a wall and through th eenclosures of nearby equipment.
2. Yes and no. It is better to have the TVSS as close as possible to the bus with no connection leads. The problem with the CB types is they are realitivly small in size (K-amps per phase) therby reducing capacity. External devices or add-ons can be much larger in capacity, but the lead length to connect them to the buss nullifies its efectiveness.
The best TVSS units are built into the panels. For home use the best IMO are the ones supplied by the POCO in the form a collar at the meter socket, or in some cases the POCO will allow the owner to supply them.
For a service entrance types you want something in the range of 100K-amps per mode or larger.
I have researched all over the Internet but have not found a webpage where they do the actual testings of all these TVSS.
(It is kind of similar to car crash tests, the car mfg can say anything they want but only a government crash test ACTUALLY tests the product).
I would appreciate if you could direct me to a webpage that shows the ACTUAL testings of all these TVSS's and pictures of them being "damaged" (and therefore proving that they performed as they should).
The bottom line is I would appreciate link to the "Crash Tests" of TVSS's.