Coordinator node requirements

Hi, I would like to use a cross-cluster-search. In the setup i will need - the coordinator node will be a separate server which will only be used to query the clusters and not store data itself (due to security limitations - where i want access only from the coordinator node to other data centers and i don't want data centers to have access to each other).
First, will this setup work? is this recommended to work like this?
Second, what should be the requirements of the hard ware to this node? it will need to receive all the responses from all the clusters so it mean it will need a lot of memory? what else?

Thanks