Re: First .22 setup (try #2)
Well, I grow tired of typing the pro's and con's of each rifle as I've done it a few times now in detail. You can probably find my own writing on them both by running a search. I'm not trying to be a dick, I just don't feel like typing it all again.
For your purpose, just about anything will do. I will suggest that you give the 452 Varmint a good hard look and consideration though.
I suppose that means I should answer your question on the differences between models though, so here goes nothing!
First off, there are three different action types, and while all are similar, they are also all different of course. There is the 452, the 453, the 513, and the newest is a 455. 452 is the model everyone loves so much, so it's natural that CZ is trying to phase it out with the 455
These are the two models to look at; the 513 is a bare bones 452 as far as anyone can tell, and the 453 is a slightly differnt 452. If you wish to know more, look into them through the search function. Again, not trying to be a dick...
Anyways, the American is a skinny barreled 452/455 with the straight comb styled stock of the 452 Varmint. The Lux is a longer skinney barreled version (24" IIRC) of the 452 with a curved comb. Not an ideal stock, but that's subject to the user's preferences. There's an Ultra Lux which has the same everything as the Lux, besides an even longer barrel. The Lux and Ultra Lux both have very nice open sights that can be easily adapted to aperture should you wish to do that. Side note, those ar the 452 models, the 455 models that have open sights are of lower quality. And lastly( of the models you asked of, but not of all models available), the Varmint is the only model to have a heavy barrel. And it has the same stock as the American's.
I would usually type loads more but i'm feeling sluggish tonight. I hope this all helped, good luck!