Honestly dude,
Nissan Cars, Trucks, Crossovers, & SUVs | Nissan USA breaks this down perfectly. No confusion. You won't pay too much difference compared to buying new, the price margin on new is like $5k But here are some answers and opinions.
Both sport models have LSD.
Yes, you're not getting anything but interior appearance upgrade for 5k extra and replacing a sh1tty stereo for another slightly less sh1tty stereo.
Imho... power seats aren't necessary in a 2 seat non-reclining sports car.
The premium of the touring pkg would be better suited on some Recaro's, a JL sub/amp pkg, some BA Dls Or Rainbow components and a Kenwood or Alpine headunit.
You will pump 4x the wattage with NO DISTORTION. Both base and touring have distortion at high volumes, the bose hass a little more clarity because its paper cone sub is seperate from the component and the weak azz amp is available. Upgrading a touring model isound system will cost double in labor than base due to the system being really ground in to the car. (More work)