Are there any xrumer gurus in here? can you answer a few questions for me?

Hi, I have a few questions about how xrumer works and how to avoid any ill effects to my site!

I dont own it but was thinking of using a service that does it for you, at a cost much lower than buying the whole thing.

I am wondering if you can choose, in xrumer, what forum category your post gets made to? You see I am building a site and it is a generic niche, which means I think the post would stick in the off-topic category of any forum. I think it would do well in the other categories as well, but not as good. Or if anyone thinks the off-topic forum is no good, tell me!

Also, on one of the service sites they talk about doorway pages and how they go hand in hand with xrumer.

What are they and why do I need them? Is it just simply creating web 2.0 sites to link to instead of your main site?

And finally, I dont want to use it to get backlinks, I want to use it to get my message posted in all these forums. I still want them to be able to get to my site. If the "stick" rate is lower for posts with links, is there a way to not create "clickable" links in all the forums.

Thanks so much!
Ashley