A:Answer Oops, meant to answer the other two questions too.
For headset, I have never heard of a two way radio taking a headset that couldn't use a mic headset. However, even if these radios can only use the non-mic headset, the built in mic should still work.
You can use non rechargeable batteries but of course if you do you shouldn't try charging them if you do. Bad things happen then. Leakage, fire, 'splosion.
Also, since these take AAA, expect to replace them frequently if you don't use rechargeables.