I have no C2 but on my XA2,
-the keyboard can be swiped to quickly change layout.
-there are words suggestions one can just click to quickly chose.
-there are other keyboards in Chum or Storeman, which are official alternative 
app stores for SFOS.
If it is not the case ATM, it might come on the C2 too.
Do you have a link to a page on the official Jolla website that says those things are official alternative stores as well?
If they are official stores, why are they not preinstalled on my phone?
If Jolla Store and the android apps stores are preinstalled, why are the ones you mentioned not installed?
There are no web pages for trust and friendship.
Collective effort cannot be preinstalled. Nor installed.
It doesn’t, no way to autofill in SFOS. Though you can copy password / username / TOTP from cover.