Good deal on the DT. First, look at your tires. If they are from 2012/2013, then you might consider a change. Maybe the same thing for the CVT belt.. it is probably about 6 years old now. do all the typical stuff: oil change, gear oil change. Check the plug and airbox... 3k miles is not a lot.
I think the seat cable thing is a typical failure on this bike. On my bike, the cable broke. So the second owner took the right side rung off, and left the left side rung but attached a cable to it which he snaked out under the plastic on the left hand side. I pull that cable to pop the seat. I actually purchased a new cable set, but I am not sure I even want to fool with it.
I have a seat pad thread somewhere in here... I added about 4" of legroom with it, and have ridden it for 750 miles now.