phpfiwa is being phased out AFAIK so the lack of a folder would only be a concern if you had old feeds to import or you wanted to go against the flow and enable the disabled phpfiwa feed engine in emoncms.
The spinner on the feeds page is an issue, is there any info if you hit F12 in your browser? (actually I’m not sure if dev tools is F12 in Firefox)
@TrystanLea has just helped find a issue with a input table on the No Inputs and /var/log full within 1h of boot thread, perhaps you could do the same checks focusing on the feed table.
sudo redis-cli flushall
is worth trying, the same can also be done from within emoncms on the admin page, there is a flush button on the right of the redis section.
[EDIT] Actually, since you can query your input and feed table from the command line it looks like your mysql tables are ok, hopefully @TrystanLea will have a further ideas if flushing redis doesn’t work.