I am using dell"s
You can replace the hard drive with a 2.5" SATA SSD, yes. There is no option for adding a drive -- no M.2 socket, nor a second SSD slot, so the drive has to be replaced.
Yes, you can. Just follow these instructions : www.laptopultra.com/.../
then you would make it :)
You could contact our sales team here and order the SSD - http://dell.to/MTTc4z
Alternatively, find the link for compatible SSD's from Crucial here - http://bit.ly/2hUb3LZ
Also, please click my DELL-username and write me a private conversation with the service tag and your contact details(Name and Email) for case records.
Let us know if you have any other queries.