Let's say you have a oldsitemap.xml which you don't want search engines to crawl; instead you want it to redirect to a newsitemap.xml using .htaccess. Is it okay to do so? It's gonna hurt ranking, right? Please suggest, thanks a lot!
If you have OLD site map which you don't wants to get Crawl to Search Engine you should have to redirect to new created site map or you can disallow it's via Robots.txt it's will heart your Ranking for a while but whenever your sites gets crawl regularly it's remain with the same old ranking may be increased.
No it will not work, have you got an account with Google web master tools? If so you can just add a new one in?
why you are making this change ? you can remove the old one from your google web master tool and add the new one or add a new one additionally to your webmaster tools account