Couple of renice questions

Hi guys. I've got a couple of questions about nice-renice....

1) Is it possible for root to increse the range of nice-renice from -10 and 19?

2) I notice that a normal user can lower the priority but not raise it, even if it were to a value lower than what it originally was (doesn't make sense...)

E.g.

12345: old priority 0, new priority 19

renice: 12345: setpriority: Permission denied

As root, can you specify that normal users cn raise a nice level to (say) 0?

3) I remotely raised the nice level of a CPU intensive process to -5. Soon afterward the remote connection failed to respond and I can't log into the computer anymore :-(. The computer however is responding to pings. Should I call up a colleague at work and tell them to restart the machine? I have no idea when it will finish, even if it hasn't crashed the machine.

4) Is there a way of automatically setting nice priorities through a script of some kind?

I've found that my jobs get done faster if I get each CPU to solve them serially rather than in parallel. The reason why I just execute a list of them instead of one by one is because I don't know when each one will finish and it saves time to not let the CPU idle at all.

So what I'd like to do is renice 1 task to 0 priority, the rest to 19. When that task finishes, a pre-buttigned one gets reniced to 0.

Thanks.