Post installation

Hi all,
I'm hoping to get an intelligent response to this as it is highly vital to the structure of my website. Here is how my site was structured from the beginning.

I created a folder in my root folder called "subsite" - This was a test for me to get my drupal skills up and running. to access this site you go to : www.example.com/subsite or, www.subsite.com (which redirects to: example.com/subsite)
The site ended up pretty great, so i did some link exchanges with good blogs and I am receiving a steady flow of traffic to my site after just about a week, plus people subscribing to my rss feed.

When I felt ready to begin construction to my main site I was in a bind because I didn't want to delete my previous installation, and figured out how to create a new drupal site under my original installation using a single directory. I created a new folder under my old drupal installation: /subsite/sites/www.example.com.home. to access my new homepage you would have to go to: www.example.com/home. And when you enter www.example.com it redirects automatically to www.example.com/home. (Furthermore, there is a link to www.example.com/subsite on my site, and vice-versa. For search engines.)

If I want to be search engine optimized, will it affect my ranking or or the search spider system if my main url, www.example.com is a redirect to a folder that is in reality BELOW other content on my site? How can I attempt to fix this issue within my own server and not with my domain registrar.

Is there a way to prevent anonymous users posting comments on forums without preventing them from posting elsewhere on a drupal site?

I can't figure out how to set Clean URL for IIS5.0. I have gone through http://drupal.org/node/3854 but that can't help. Can someone tell me how to set the Clean URL for IIS5.0. I also have installed ISAPI Rewrite Lite but I don't know how to use it.

To build a Taxonomy URL start with taxonomy/term/". Then list the term IDs, separated by "+" to choose content tagged with any of the given term IDs, or separated by "," to choose content tagged with all of the given term IDs. In other words, "+" is less specific than ",". Finally, you may optionally specify a "depth" in the vocabulary hierarchy. This defaults to "0", which means only the explicitly listed terms are searched. A positive number indicates the number of additional levels of the tree to search.

I have authorize.net set up with my account info added to drupal, etc. When I run through the purchase process, it throws me over to https (https://mydomain.com) where I get an access denied drupal error and I am logged out of drupal (i'm still logged into the http side). I understand that the session isn't carried over from http to https, but I haven't done much work with https and carts so I'm not sure where to go from here.

-Thanx

Hey guys I'm relatively new to drupal and have a quick question. Does anyone know how to deny duplicate node titles? I am making a website to review different kinds of food and I don't want users to double post the same food. I am using cck for my "food" node. When the user goes to add a new food I want an error to pop up and deny them submission if the food name already exists. Any modules for this? I'm a noob so I need pretty clear instructions...thanks guys!