As far as I know, R=1. Rusty is likely the best to comment on this and things may change before/after release, but currently there is no way to specify R for index lookups, and only the minimal set of replicas is queried.
Technically, when you perform a write, Riak will always dispatch to N replicas. W simply requires Riak to confirm W writes before responding to the client. So W=N allows you to know N index sets have been updated, but it's not strictly necessary. At the end of the day, indexes are eventually consistent like the rest of Riak.
Right. I'm just saying that if I write and I want to assume a query after that write will include it, I will need W=N since R=1. Which is fine... but tricky. W=2,R=2,N=3 has been my favorite combination but I guess there are always cases to try other setups.
Technically, when you perform a write, Riak will always dispatch to N replicas. W simply requires Riak to confirm W writes before responding to the client. So W=N allows you to know N index sets have been updated, but it's not strictly necessary. At the end of the day, indexes are eventually consistent like the rest of Riak.