Hello, I see this mentioned alot in this thread: can anyone share what it means exactly to be employed under outsource contract?

1. Are you reporting to ST or the boss / lead of the attached company?
2. Do you lose out on employment benefits (package, leave, etc)
3. Does it mean you have to stay for that period since it is a contract (cannot leave like perm staff)
4. Who performs appraisal for your work, and usually what performance bonus can we expect?
5. Is ST a good place for experience / resume buff despite the supposedly lower pay?