If i have a site which has like a main portal page, then 4 completely different niche subpages each with their own image folders, etc...is it hurt my ranking to call each of those pages .index? In other words it should just be the name of that subpage, and only the main page should be .index?
Make some subdomains for your "4 completely different niche subpages". Then searchengines will see them as different sites.
no not at all. you can have the index for those as they will be treated as index pages of the sub-directories. but while using it for backlinks or linking, i will recommend doing: http://www.domain.com/ http://www.domain.com/niche1/ and not http://www.domain.com/niche/index.html
Sub domain should only be used when the content is quite large i.e. there is ample amount of content to be added and which is completely different from the content of the parent website.
you should explain what you mean... subdomains are great, but you mean like index1 index2 ?? that is bad, yes. but in different directories its always fine.
if its in different directories, you don't need to name them index1 index2 etc. anyway, i won't try to explain it to someone with such a presumptious attitude. good luck.
I mean is it okay to go "example.com/index", then go example.com/niche1/index.html and so on for niche 2, all that? Thanks for the helpful answers all.
If you are putting the index files in different directories, like the following example: ...Then yes, it is perfectly fine.