It's a lower-end bike but still worth money. As far as the tuneup, if you don't have the tools/experience to do this yourself you're better off just selling the bike as-is and letting the next person fix it up.
Give it a bath, take some better pictures from the driveside (right side) and I'd say you could probably get $75-100 depending on your location.
Also, it's not a Schwinn in any way shape or form. Just a Raleigh Sportif.