Do each application within one App pool get unloaded in IIS 7.X or does it affect the whole app pool?
if i have one hundred applications under same app pool are alls of the applications always loaded?
Loaded or unloaded?
All applications within the same App Pool may run as part of the same worker process.
So a crash in any one of those applications will take them all out at the same time (at least for as long as it takes to start a new worker process and serve a request).
Second part: If you have 100 applications in a pool, they're always considered part of that pool, but demand-start behaviour might apply - ASP templates might not be compiled until called, .Net code won't be exercised until a particular function is run, and so on.