People who hold the title "news editor" at a radio station may do any of a variety of editorial tasks, and they may be at any of several levels of power and responsibility. At the top level, radio news editors manage the news department. They make high-level decisions about what news the station will report, give assignments to reporters, make hiring and firing decisions, etc.
At the bottom level you have people who are the radio equivalent of a copy editor; I once worked part-time as such an editorial peon at WFIU, the NPR affiliate at Indiana University. I've talked to people who've worked at commercial radio stations, and they tell me that the procedures at public radio stations aren't drastically different than theirs.
My workday started at 5 a.m. The first thing I would do was rip down the weather forecast that came in on our big printer and take it to WTIU, the TV station. Then I went back to the little editing office and started up Mercury, a word/data processing program that was hooked up to a satellite feed from the Associated Press. I found the latest weather forecast and re-wrote it in a conversational style so the announcer wasn't reading stuff like "Partly sunny, low clouds, temperatures peaking at 30-35, SW wind 10 mph."
I took the weather re-write to our announcer. Then at 5:25, I went into the other room and turned on the Gentner machine and the reel-to-reel tape machine and called the AP bureau in Indianapolis to get the audio feed at 5:30. It was kind of like a modem set-up: the phone hooked into the Gentner, which did some sound processing to adjust for the phone messing up the bass and treble, and then the audio was recorded by the reel-to-reel.
After that, I located the local-oriented stuff that came down from the AP satellite. I had to write three different newscasts to be read at 6:06, 7:06, and 8:06. I picked out appropriate stories, copied and pasted them into a word processing file, and then I made it fit whatever time I had to fill (usually about 3 minutes).
I edited the stories for typos, sentence length (can't have a 3-line sentence or the announcer can't get through it) and word proximity (can't have a bunch of words with "s" or "f" in a row or the announcer spits on the microphone). I added phonetic pronunciation guides in front of foreign or complex words; our announcers were generally opera voice students, and they sometimes had a wonky sense of English pronunciation due to having had all that French and Italian drilled into their heads (a native New York announcer once pronounced Cincinnati "Chinchinati" on the air).
When I selected stories, there were certain issues I had to pay attention to. I couldn't just run any semi-local story that came in off the wire. Sometimes the AP sent us stale stories, or stories that had no real point. Also, WFIU ran exclusively policy-oriented stories; they didn't run blood-and-guts stories (like car wrecks or murders or robberies) or long profiles or other semi-literary style stories. But we almost always ran stuff that had to do with unions or IU.
And sometimes I got stories that I didn't know what to do with. For instance, we got a story about some mental patients that were released from a hospital in Indianapolis and ended up attacking some people & robbing a store. Blood and guts, right? Don't run it, right? No, Margaret (my boss) told me the state was thinking of shutting that particular hospital down and there was a big controversy over the closing, so therefore, the mental patients' mayhem story qualified as being policy-oriented.
The job wasn't difficult, and for a starving student, the pay was decent enough. The hardest part was being able to function so early in the morning. I developed a whole set of editing skills that I probably can't even employ unless I'm half asleep.