You’re probably fine with just the release apk - if you don’t know what the debug and nouserlib apk are or do, you probably won’t need them (in my experience, at least). I didn’t need to install a dictionary, just turn on an autocorrect setting.

it sounds like it used to have the equivalent of GBoard’s globe icon you could click on to switch languages but not anymore? You have to go to settings and uncheck English and check whatever other language you want to use?

When I deselected “use system language” a list of languages came up and I selected a couple to try with. After selecting the languages - and I don’t know if this is a setting you can change - but I long-pressed the “,” (the comma on my QWERTY key setup) and a menu came up that let me select (by gliding to) a globe icon which switched languages.

And, it seems like I can do the equivalent of Shift + key on a standalone keyboard (for example, to get 1 instead of Q), but I don’t know how to, or what that’s even called.

Do you mean by long pressing the letter? Some settings are in the Preferences menu in heliboard setting menu - ‘key hint’ and ‘key popup on press’ I think control what you see.