There is no way to reload wagons or move them. Maybe in older versions.
As far as removal, either building (q)ueries or building inven(t)ory, move cursor near wagon, hit - to disassemble. A carpenter will come by and turn it into three logs.
As far as animals.... set up an act(i)vity zone set to pe(n)/pasture, and assign the animals to it. This keeps them from starving long enough for you to (b)uild a (w)orkshop for b(u)tchery, and then go into the stock(z) screen, select animals, and designate the animals for slaughter... I think it's (b) but it should say on the screen. When in doubt, read all the menus.
In short, read the wiki ._.
This. Although you can just pasture them somewhere with grass or moss and they'll stay alive as long as they have it. Then you breed them and have a farming industry.
You can load it back up and move it around. I forget what the button for that is though. I usually just disassemble it with q x.
Also, where did you hear this. This is completely wrong.