+5 on using it for fermenting.
As for pulling the spear, there's threads here explaining how to do it. I've done it several times, so I find it pretty easy. You only need a few items to do it.
As for fermenting in it, you have some options on how to fit the airlock. The easiest would be to get one of the large universal bungs/stoppers (not for Better Bottle carboy's, the other one) and simply jam that into the opening and install an airlock. You can also get one of the Brewer's Hardware sanke fermenter kits if you wish. I have a few of those still, but I've been using ones I designed and had made at a machine shop (TIG welded). I have mine setup with a liquid ball lock fitting, that I can send a dip tube through, and then install the post onto it. That way I can use a CO2 push to move my brew from fermenter to serving keg without lifting it one inch.
Of course, I do have a gas post fitted to the keg itself (in the top)... You can use the Brewer's Hardware kit in the same fashion, it just takes more tinkering.
With the orange carboy cap, you can fit the offset nipple with a barb and connect a gas line to that, and then use a racking cane to get the beer out. I did that for several batches before getting the custom kits made.