First of all, let me comment that your practice should be questioned. Enterprise apps normally are running all the time. If you suspect memory leaks, then try to understand why and fix it there (starting with gc log, etc.） If you have outofmemory triggered dumps, you can load them up using IBM support tools refer to this IBM link: Debugging from dumps.

Now with your second question. Normally you use some kind of load balancer. Modern load balancers allow you to take nodes off the rotation so that users will be routed to other nodes - check the load balancer admin for details.