Go for it! If you're just gonna keep it for a few months those costs sound very reasonable. Plus, you sound like you are probably not gonna be driving it
every single day, so it'll probably be cheaper than renting a car or taking a taxi.
Now, to answer your questions:
1. I'm with my second s-series truck and I've always liked 'em a bunch. No experience with that combo of engine and trans(mine have both been 4.3L and 4spd auto).
2. I think it is definately worth buying. The peace of mind for your family alone justifies that cost. Plus, maybe you can make a few dollars by moving sfuff for folks, which will help offset your costs. When younger I was able to get bunches of pizzas and beer
, and a few dollars here and there.
3. I think it'll be a great candidate for ecomodding. Like others have stated, you should be able to pull some very respectable mpg's with just a few tweaks and mods.