Switch from wordpress.com to wordpress.org

I have a wordpress.com blog that I was thinking of converting to wordpress.org. I did a search for instructions as to how to do this, and came across this forum topic: http://wordpress.org/support/topic/switch-from-wordpresscom-to-wordpressorg?replies=12

but because it is 4 years old, I didn’t know if it was still accurate as to how the process works now. I would also like to be able to work on the wordpress.org blog and perfect it before launching it. So I would like my website address to still point to my wordpress.com blog until I am ready to launch the wordpress.org blog. Is that possible? And will I be able to carry over my CSS customizations from my wordpress.com blog over to my wordpress.org blog?

Thanks You!

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