This would have been better in a new thread. :-)
slitweb Currently I am also wondering how exactly caching with --wpredis is done.
All page caching on WordOps is handled via conf files - different configurations are included depending on which option you use (--wpredis, --wpfc etc). If you look at the site level conf file you'll see how this works (wo site edit <domain>).
slitweb I know that Nginx Helper plugin also gets installed. And I have always been wondering what this does as there is still no documentation on this.
Nginx Helper isn't part of WordOps, it's a plugin from the main WP repository - lots of info on it there:
https://wordpress.org/plugins/nginx-helper/
Short answer is, it's (mainly) for handling purging of the page cache. It doesn't 'do' any caching.
Re 1. Yes if you want relevant pages to be purged, e.g. if someone publishes a new post and you want the homepage to immediately show that new post etc. Pick redis if you're using redis for page caching, pick nginx if you're using nginx for page caching. Simple as that. Again, this is for purging, nothing to do with selecting page caching method.
Re 2. From the Nginx Helper plugin? Probably, never tested it with multisite. You can check by purging and then checking a page from each site before/after - look at the headers returned to see if there is a hit or miss from the cache.
Re 3. Depends what you're doing with those. Choose where you want page caching, don't just do it in everything or it will be a mess. :-)
