While so computer program can know good writing like a human, this site can be a quick , free, online resource for checking spelling and grammar. No sign-up required.
podcast sounds better with a bit of music in it. Or some special audio effects. But the problem is that legally you can't just use any mp3 file from your music library since you will be breaching the copyright of the original artist. So move away from using your favourite bands - and look into the wide range of "pod-safe" or creative commons audio that are out there on the web.
Here are several websites that are worth a look - some provide whole music tracks, others provide sound effects.
STORY HIGHLIGHTS
Bullying is just as common at public and private schools
Violence is much less common outside of public schools
One in 10 students admit to bringing weapons to school