latchet

My computer is not working properly, too many issues to ask for help. So I
bought a new hard drive to put in as a master and run the other as a slave.
I have XP Pro on the old one with all apps etc on it. What I want to know is

if I install a new O/S on the new hard drive, will I have issues with the
O/S on the slave. Second will I be able to use all the apps on the slave or
will I have to reinstall them all to the Master?

After I install the new drive I want to get rid of the O/S on the slave can
you tell me how to do this. I can find answers if it is an upgrade from a
previous version but not as a standalone install.

Can you give me advise on the best way to tackle these issue please.