OK, first of all, love these questions -- and nothing dumb about them.
The hole drilled laterally through the post on the speaker connecter is really for bare wire. Thread the wire through the hole, and then tighten down on it. You don't need to use the hole for bare wire, however, (you can just wrap it around the post and then tighten down on that), but as far as I am concerned, that's the only thing that that particular hole is good for. Thus, if that particular hole is too small for the guage of bare wire you have in mind, you can still use bare wire, you just have to avoid the hole.
If you want to use spades, you'll need a spade large enough to accomodate the width of the post. Sounds like you've got posts of materially different widths, so, you can terminate with different sized spade terminations. You don't really want to thread 1/2 of a spade termination through the center hole in a post as -- as you've discovered -- you really can't tighten the screw on it without damaging things.
Bananna plugs do not go in the hole drilled through the side of the post. You don't want to put them there. Rather, they go straight into the end of the post. To use a bananna plug, in other words, the post needs to be hollow -- and it's into that hollow end of the post that the bananna plug goes.
So, I guess in an effort to recap, you can always use bare wire. Wrap it, thread it, what have you, tighten it up and squash it down, and you'll have a pretty damn good connection. The hole drilled laterally through a binding post will assist in this quest, but it is by no means necessary. If you're looking for terminated wires, sounds like you may need asymetric terminations (just made that up -- but, basically, something different on the amp end than on the speaker end. This is quite easily done.) You could go with different sized spade connecters. You could go with spades of the appropriate size on one end, and bananna's on the other. You could use banannas on both (although it is not clear that the amp-end is designed to accept banannas). You get the idea.
All things equal, some say that bare wire is the best connector -- as there is a whole lot of smashed up contact area for signal transfer and no intervening mechanical connections with the potential to fail. Others will say that bare wire leaves open potential vectors for oxidation that will degrade the signal over time, whereas a solderd connection to a gold-plated termination eliminates the oxidation factor. Each true, so you takes your pick and goes with it.
Finally, depending on the wire you go with, and where you get it, you should be able to acquire any old configuration of termination (or none at all) your heart desires. As long as you know what you want, any dealer you're talking to should be able to figure out how to make it happen. Helpful...?