As far as the "sword inspection" goes, it was pretty much non-existant for my company. The only thing I can remember that even approached an inspection was a Sgt telling me my sword was too long, and then another Sgt telling me it was too short. I think the Marine Shop makes a much bigger deal about the "inspection" and not having your sword engraved than is really warranted. I ordered mine from the UK already engraved, and there wasn't any problem.
As far as which sword to buy, there isn't much difference between WKC's sword and the Spanish sword. Wilkinson's swords are a little bit different, but you'd have to look closely to tell, with the exception of their high-end hand made products ($1300 for sword and scabbard vice $550-$700 for the machine made version). Wilkinson apparently ceased manufacturing swords last September though, so I don't even know if you can find them anymore.
As far as the sword and the Sam Browne belt, that is an acceptable combination. Didn't presonally wear a sword at my comissioning, but I suppose it might be different everywhere you go.
Bottom line, don't sweat the inspection and sweat which sword to buy even less. Both appeared same in quality and design, the biggest differance (as far as I saw) being the size of the stars on the grip rivets. I will say that it might be nice to purchase from a source in/near Quantico, as at least one person in my platoon had to have their sword repaired during TBS.