Translation:They are subscribing to your newspaper at least.
That means something different. If you say "at least they are..." That means, they're not doing a lot, or they're not so great in other ways, but they are doing this one good thing, they're subscribing to your paper.
When you say "They, at least, are..." that means, they are subscribing to your newspaper, and other people aren't.
True. But the German sentence could mean either of those, depending on which word you stress: "Wenigstens abonnieren sie deine Zeitung" is "They, at least, ...", while with neutral stress (just regular word stress as in "Wenigstens abonnieren sie deine Zeitung") it is "At least they are ...".
Because this verb requires Akkusative. It is similar to russian language and when you translate directly it would be to subscribe ON something, but we do not speak this in english =) Some dictionaries have symbols next to verbs, when it is (vt - verb, transitive) then it requires Akk.
Am I the only one who finds "are subscribing" weird? To me, that means that they're actually in the process of arranging the subscription, filling out the paperwork etc., and if they already receive it every week, I'd say "They are subscribed to..." I'm a native English speaker but my English is slowly getting weirder the longer I'm away from home.