Replication server for patch application

[Logan Ramasamy_1]

I am a Oracle DBA. Our production Oracle server (oracle 9i) is running on HP-UX 9000/ 11i, (rp2470, aprox 3G in size). I understand that Oracle replication is high availability solution. However, my manager is pushing me to build one for Unix patch application. His idea is that periodically, switch over to the replicated server. Apply patch on the production server. Then switch back. I do not think that this is an easy job. Though, we are 24X7 shop, we close for New year, Good Friday, Memorial Day, July 4, Labor day, Thanks Giving day and X-mas day. Having said these, my questions are, (1) How many patches one has to apply on this box/ OS periodically (whatever needs to be applied as per Oracle manual, has been applied already during installation ).
2) How frequently these patches have to be applied? (3) Can't they wait for one of those holidays? (4) What will happen if we do not apply patches? (5) What mandates the application of patches? Please enlighted me.