I'm not a native speaker (I've just started learning the language), but, according to the introductory lesson attached to this unit, the "me-" prefix makes a verb explicitly transitive. For example, "saya makan" = "I am eating" (no direct object), but "saya memakan ikan" = "I am eating a fish" (fish = the direct object). Apparently the "me-" is often optional, and makes the sentence sound a bit formal. I think this is the case...I'm not positive.
I'm thinking that may be necessary if there is a direct object, but we would need that to be confirmed by someone who actually knows the language.
Meminum/memakan is not wrong, but it's redundant. There is no such thing as berminum or bermakan, and therefore no need to use a me- prefix.
Is "itu" really so non-specific that it should be translated as "the" rather than "that" so frequently?
James, I was wondering about this, too. It sounds strange to me to use "itu" as "the. (so often)
This is something that has given me endless trouble since I started learning Indonesian. My sense is that native speakers tend to use -nya quite liberally to mean "the." The problem is that in formal writing, -nya is used very sparingly (and only to signify possession, I believe).