I would like my subdomain to suggest straight to a folder. That's if the HTTP request is built to apple.example.com, I would like the reaction to function as the items in example.com/apple/index.html, although not a 301 error. Is it feasible?

Yes, this really is the objective of tools like ISAPI_REWRITE. My webhost (orcsweb) uses exactly this method.

-OIsin

Yes, but you have to make certain that the server has the capacity to support virtual domain names. I'm not sure enough relating to this, however the mod_rewrite can be done without redirects.

# Internally rewrite <subdomain>.example.com/<URLpath> to example.com/subs/<subdomain/<URLpath>
RewriteCond $1 !^subs/
RewriteCond %{HTTP_HOST} !^www\.example\.com
RewriteCond %{HTTP_HOST} ^([^.]+)\.example\.com
RewriteRule (.*) /subs/%1/$1 [L]

You are able to serve content from the folder or send a redirect towards the client, but AFAIK you can't do both simultaneously - you can't serve content and in some way alter the url in browser simultaneously.

If it might be possible, it might most certainly result in many security exploits.