Deductible Expenses for Home Business

I recently started my own business as a self proprietor. I will be running this business from my home and recently made some upgrades to my home in order to accommodate my new business. Specifically, this includes installing a new dataport (ethernet line) in my work area (a requirement I would not have otherwise installed) and a permanent door to provide noise protection for work that requires a quiet space.

 

Are these home upgrades deductible as business expenses? Additionally, how do I determine if any part of my monthly mortgage (principal/interest) is deductible as part of this business, as I will be using a portion of my home for my business?

 

Thanks for any insight you might be able to share.