Upgrade to pro on wordpress.com

Hi to all, I need information about wordpress.com.
I am using wordpress.com for my blog but now I decided to have a main domain name, so i want to migrate from wordpress.com to my host or I could choose to upgrade my current blog on wordpress.com.

My questions are:
– If I choose to upgrade to pro version I can mantains all links shared on facebook,twitter and others? All shares did using the plugin installed on wordpress.com
– If I choose to upgrade to pro and at the same time choose to mapping my own domain, I could mantain all links shared on the social networks?

To have the shares are is very important for me!!!

I write here because I don’t find any answer on google about this argument.

Thanks in advance.

Giacomo