Display model laptop warranty less than 1 year? Power adapter replacement or repair.

I purchased a display model Insprion from Office Depot about December 15, 2018, but service tag show warranty started March 29, 2018 and expires June 28, 2019.  Will warranty be honored for 1 year from purchase date if I have original receipt of proof of purchase?

I wanted to get warranty for a charger adapter,  do I have to send it in for repair or will they give me a replacement first then send in the adapter after? Because I need a computer to use and don't want any down time. 

And if I get a replacement adapter, but Dell determines it's not cover under warranty for whatever reason, may I return the adapter so I don't get charged? 

Thank you for any advice and help.