Awesome, an excuse to talk about the books I have aquired

.
This is indeed the correct place for that information. Welcome Nicolas.SecondApocalypse, to the TSA forum.
Once I have a bit of time, hopefully tomorrow evening, I will post some photos of my collection so you can see whats out there and what your options are.
Just so you know, what you're looking for are Hardcover, First Edition, First Printings (aka Hardcover, First/First).
TDTCB might be the hardest to get, and most expensive. Not many unmarred copies of that one laying around.... Or at least not for the price I wanted to pay.
One thing that you will encounter is the softcover "uncorrected proof" (you mention this above). I wasn't sure what to make of this either. Both have number lines that include the "1", which is indicative of a first printing, and the cover is the first edition. All my books are USA with "first edition" printed on the inside. I'm not really sure how 'authentic' my versions are, but for all the looking I did, it was the best I could do and I'm happy with my purchases.
I have not read the uncorrected proofs at this point, but the page count is the same, so there is little chance that there is any additional information/words within the pages. If you're looking for something like that, you'd need to find something much more rare, like an unpublished copy of some kind, bound on computer paper

, and I doubt anyone but Bakker himself has those still.
I've have the first/first hardcovers of all 3 of the PoN books as well as the three softcover "Uncorrected Proofs" of PoN. I have an ARC of WLW, and ran out of money before I could find/purchase the ARC of TJE.
TJE and WLW should be easier to find in first editions since they are recent, and might not even be in their second printing. At least for those two, I am pretty sure the Canadian and USA version where released simultaneously so it shouldn't matter (either is equally "authentic"). The covers might be different, but again its personal preference. I'll be looking into getting proper copies of the Canadian hardbacks from AE once I get some more cash.
If you are looking for great display sets, go with the hardcovers. The original covers, drawn by David Rankine, are by far the best of the series, and the hardcovers are just sturdier.