All the versions we have in our area except one let the callers basically sell their items. Usually it seems to make them more interested in the item, and they can have some give-and-take with the host and give some details if things aren't clear. There are also regulars who call in, and it seems like they have built some kind of community up for the two-hours-on-a-weekend or 30-minutes-on-a-weekday that the different ones do it. There's a few who call in who can't articulate fer nuthin' but I don't think most inarticulate people want to call in. Most of the ones who have trouble talking in this area are elderly, invalid, or have some health problems, which often also becomes something else to talk about (and fill time, some days).
The only one I've heard that read all the items was droning and uninterested. Probably some of the items were already sold anyway, because you had to have them into the station by the day before. Try and avoid that.
As for including business items on the air, there is the whole gamut of that too: one is "sponsored" by a local charity organization with other local commercials interspersed, a couple only have the host and sometimes a second host doing live reads. I imagine that whatever you can sell or trade (that's even what the show is about) is what determines the stations' options there.