The K400 is adequate for short text entry like when searching for shows. But the keyboard feel is rubbish compared to a desktop or even a laptop keyboard. Shouldn't be a problem unless you're planning to write an essay on it. Just be aware of what to expect. I dunno if the newer K400+ has improved on the K400, but its reviews seem to be slightly lower so probably not.
It uses a Logitech unifying receiver, so the price is almost worth it just for the receiver (receiver costs $8.50 on its own, keyboard is about $20-25, frequently goes on sale for $15-$20, was $10 this past Black Friday). I can confirm that the battery is phenomenal - mine went 3 years as well.
I suspect though that any wireless keyboard will work, as their USB...