They all come with a M.2 SSD. The 128GB is SATA version. The 256GB and up are all PCI-E version. I believe all the same Architecture is used on all 9350 machines, just the SSD is different
I have zero experience running game emulators, so even if I installed the software I don't have any games for PS2/Wii, sorry, maybe google some gaming forums. I'm sure the XPS 15 would run them way better with Quad CPU/dedicated graphics, but then you lose the small form factor of course.
I ordered a XPS 13 (9350) QHD New from Dell on Black Friday, but returned it after about a month. Just didn't seem worth the retail price. Found the identical "Certified Refurbished" laptop on Dell outlet for 40% off last month. Was nervous as to how the condition was, but it was in factory...