Depends on the store. Some would see no benefit from it, and it would actually hurt more than help (no posts/little posts is more hurtful than no forum.) If your industry is a social one where people like discussing the products then it would likely be of benefit.
For a forum software, SMF hands down. Its free, ungodly easy to customize and plenty of free mods. If you're shitting gold bricks, can hire a developer and want to pay for everything SMF does for free go with vBulletin.