is 2 ORACLE_HOME good?

[yxez]

Shutdown what?

If you shutdown the server your database will all be shutdown

You dont need seperate software to shutdown a database and the other not

If you have 10 instances running are you gonna create 10 ORACKE_HOME?

Sure you can, it´s up to you.

pando...I mean shutdown the db....coz there are instances when
one dabase hit a bug....then u apply patch independently...and some
maybe maintenance of each application itself...without disturbing
the other