Index Routing Allocation basics

Hello All,

I am trying index routing allocation option available with elastic search.
I have gone through the docs available on net, this group and looked
through the test cases. But could not come to any substantial conclusion. I
have been working with Elastic Search but not from a long time. Hence I
would be thankful, if below queries are answered;

1- Does the Index routing allocation work only after the Index is created
or can I specify a routing allocation policy and than create an index.
node1, index.routing.allocation.include.tag: node2 etc.

2- a- If the routing policy is applied at the index creation level, than
shards should not be created at exclude nodes. And rebalancing of shards
will happen between the include nodes. If only one include node is
mentioned than no rebalancing should happen hence faster index creation.

2- b- If routing happens after the index is created and rebalancing of
shards happen. Than what is the usefulness of routing as it defeats its

3- Is it possible to use Transport Client and bulk index the documents with
routing option. If so how?

Please suggest.