Will having multiple homepages help or hinder rankings. For example: If I have index.htm, index.html, and welcome.htm? Is there really any reason to have all those? I think most servers are set up to use index.html as the homepage, are they not?
You can have multiple index's if you like, provided they don't contain duplicate content word-for-word they shouldn't be a problem. Though, I don't know why you would want more then one.
I dont see any reasons to have all those, espacially if they all have the same content. In that case it only hurts more then it helps because of the duplicate filter search engines would use. Rename the files instead and use only one index file, the other files should be named with your desired keyphrase to be better found by the search engines.