Sak is much more common, ting isn’t much used except for in some expressions.
Which is which? Am I right in thinking that "talar" is typically closer to "talk" and "pratar" to "speak"?
Other than set phrases ("talking shop", "public speaking", "talk the talk", "speak a foreign language", etc.), I can't think of any differences in English.
Do you have any Swedish examples of where one would sound natural and the other wouldn't?
The other way around, actually. Tala = speak, prata = talk.
When it comes to speaking a language, it's often more common and fitting to use "tala". When delivering a speech, you also use "tala". For common chatting and talking, use "prata". Just like speak, "tala" sounds a little bit more serious.
Samma behaves like the possessive pronouns; it is followed by a noun in the indefinite form (and an adjective in the definite form).
It just seems to be in a different order than the rest I've translated. Why isn't We at the front?
Because it's a question, and then the subject and verb are inversed.
Pratar vi? Vi pratar!
Why is "Are we talking about the same thing?" wrong here? What makes sak become an issue?
As you can see on top of the page, "Are we talking about the same thing?" is actually the suggested translation. It's hard to say what may have happened in your case – I know that there are glitches sometimes.
Hmm, apparently ”sak” and “sake” are pretty much cognates, except they have different shades of meaning now. And Norse/Icelandic “thing” is a little closer to our “sake” too, haha.