People familiar with Latin will know know they mean the plural. But because that distinction is not clear in English, learners can become confused and lose the distinction in Latin (a very fundamental one) because it doesn't exist in English.
Most text books I've used and taught from demand some distinction in translation, and I think that's the right way to go.
From what I've taken before Duolingo, this is the standard word order for Classical Latin - i.e. normally all the other words in the sentence come before an action verb [linking verbs usually go between the subject (nominative case) and object (accusative case) as in English].
In answer to your second question, Latin word order is pretty flexible, so I don't think it's incorrect, per se; however it is more common (and consequently probably preferable) to put the action verb at the end of the sentence.
I'm not familiar with vulgar Latin, but these differences just go to show how much a language can change:)