I am wondering what's the best setup for a forum, subdomain or subfolder? I might want to make a blog in the future at thee root. Another question, will the word (forums) I use in the subfolder or subdomain affect the keyword I want to rank for? Subdomain: keyword.domain.com Subfolder: www.domain.com/keyword/
one thing must be kept in mind that subdomains don't pass any link benefit to the domain or subfolders within. all subdomains are treated as separate entity by search engine. So in case of forum, as you will like to have a different set of entity apart from your regular services so it is beneficial to use it as subdomain. But if you want to add worth to your domainname and inner pages through subfolders through link structure from your forums pages then use it as a subfolder.
I will go with a subdomain as this can add value to your whole domain even though it is seen as a new url. It also helps that your files (pages), don't go to far deep such as domain name.com/forum/category1/category2/forum name.
The thing is that I have had my forum for 2 years now in the root.. I must change that, since I want to use the main root for CMS! Is it still possible to change make the change to a subdomain and redirecting the traffic somehow?
In case of forums "sundomain" will be better over subdirectory. As you are going to make your main domain dominate for blogs, so in this specific case "subdomain" will be better to separate the non relevant "off topic" type contents that usually are part of forums.