Cloudant is doing some very interesting things relating to querying on a CoudhDB system. They created a query syntax so that you have an option besides map/reduce [1]. I watched their webinar on it and it seems pretty slick, but I have not yet played with it. Also, it is not part of CouchDB yet so there is no option to run tests against locally to verify syntax, response errors, etc, etc.
Cloudant is working to merge many of their changes from BigCouch back into the CouchDB project, so one day I expect CouchDB to have multiple query options [2].
[1] https://cloudant.com/blog/introducing-cloudant-query/#.VLCSc...
[2] https://cloudant.com/blog/update-from-nebraska-the-cloudant-...
1. Indexes are built and appended to at read time.
2. If you change the view code an index rebuilding will occur. (A hash of all the views in the design document is taken and compared with the previous hash. So even a small thing such as adding a space will in effect change the view code and trigger rebuilding of views.)
3. No change to any other part of design document will have any effect on views.
I wrote in detail about it here (http://staticshin.com/programming/does-updating-a-design-doc...)
That being said, CouchDB does have a nice built-in in gui.