Please, I need your help, friends

I have web www.accounting-on-line.com
some pages open as accounting-on-line.com/company_formation.html
However when I place links or make registration ( for ex www.business.com)
I always put www.accounting-on-line.com/company_formation.html
Please tell me. In sitemap in Google I pointed main email www.accounting-on-line.com
Please tell me
1. does it effect SEO
2. Do I need Redirection 301
3. IF YES HOW I CAN DO IT

Thanks so much any opinion welcome

 

1. Not really, however some people do believe it can cause dup content filter to active.
2. Well i usually use them to ensure consistency for my site

3.RewriteEngine On
RewriteCond %{HTTP_HOST} !^www.domain.com$ [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [R,L]