I have seen online stores that incorporate forum and discovered that some of these forums develop a life of their own, they became something entirely separate from the online stores. That is, none of the topics discussed are pertaining to the hosting online store.

I believe that most, if not all online store owners aim to utilize their forum as an advertizing and publicity tool. Having their forum develop into a separate entity just wouldn't do.

My questions are:
1) Is it possible to "advertize" in phpBB, perhaps something like displaying random products' images, special offer items, promotion etc.?

2) What are the ways to prevent the forum from developing into a separate entity for the online store?

Thanks very much for any kind advice.