Installing a elastic search plugin for lang support

Elastic Stack Elasticsearch
1

I want to install the following plugin into my ES cluster

Do I need to install it in every node? And do a full cluster restart? Or just one node is sufficient?

2

Do I need to install it in every node?

Yes.

And do a full cluster restart?

Yes. But a rolling restart should be ok as soon as you don't create an index with it.