how can i freeze execution of thread?
i dont want to call NtSuspendThread, some interrupt would be better. Lets say, stdin input or time period (not NtDelayExecution). Can i do that with 'int'?

Can i freeze execution permanently?


would be nice for debugging. And how do i obtain FL/IP?

Look in for WaitForDebugEvent; ContinueDebugEvent; DebugActiveProcess; WaitForInputIdle(for GUI) and other similar functions in msdn(has and ".cpp" example). its combination is a good way to "command" threads and processes.
if you want to "freeze" execution permanently - create a service or driver to catch or terminate the process. But i think that is not possible if use bios interupt