I would pick option 1 or 2.
Unless you have some additional need/want for a pickup around the house, it will cost quite a bit more to buy an older pickup (still north of $15k, probably, to be in decent shape), plus maintenance, insurance, all of that fun stuff.
I don't know if either option will surpass your MDX in fuel economy, but they will get close. My Ecoboost F150 gets 21-15 (freeway/city); our 2010 Suburban gets 13-19 under the same conditions. MDX is a nice vehicle, but you'll find a nicely equipped full size SUV just as luxurious -- our '10 Suburban has just about everything you'd want or need (leather, captains chairs, heated front and middle, power fold middle, 3-zone climate, etc). For what it is worth, you'll find a Suburban or Expy a bit more spacious and comfortable for a family on the inside, I think.
To me, it comes down to do you want a little more interior room or a pickup bed? You can throw a topper or shell on the back and have plenty of covered cargo room in the pickup, but it isn't quite the same as the back of the SUV for small personal items IMO. My wife wouldn't trade her Sub for a truck even if we only had 3 kids (we have 4); I like the extra space and the versatility of the truck.
My personal choice, if you can swing new, would be to wait a few months for a '15 Ecoboost Expedition.