It's NOT EXACTLY a 75B, but the internals are similar and share many parts, and it's basically the 75B design inside. The barrel lockup is a little different, I think. The Kadet Kit won't work on the 40B, although I have heard that some folks have made them fit.
I had a 40B when they first came out, and foolishly traded it away. It was (and they are) really sweet-shooting guns, and because of the alloy frames, a bit lighter than similar guns. They also seem to be almost trouble-free. You seldom hear of ANY problems with CZ-40Bs.
The mags from a 40b won't work in a standard 75B .40, because of the weird baseplate/grip design of the 40B (a Colt specification for the Colt Z 40, which was a functionally similar gun, built by CZ for Colt.) If you have need extra mags, just get the standard 75B Mec-Gars mags, and they'll work fine in the 40B, with a small gap at the bottom.
CZ did a second production run (if not more) of the 40B a year or two after they were first introduced, but I haven't heard of any newer ones, since then.
Do use snap caps when dry-firing, as the firing pin retention roll pin CAN break with repeated battering. (I speak from experience.) You can get another roll pin at any hardware store, and you might even be able to get a "doubled" pin (roll pin with a roll pin inside) from CZ-USA, which is how they "fixed" the problem of breaking pins. I dry-fired other CZs repeatedly without a break and was a real skeptic about the rumors of their breaking until I had mine break with a relatively low trigger-pull count.
I'll eventually find one for sale or trade, and get one back.
Hopefully, I'll also stumble across a Colt Z-40 someday, for a reasonable price. Basically the same gun, but generally in DAO. They did make a few DA/SA models; the Colt DAO trigger (built by CZ) is supposed to be very nice.
. Got mine for about the same and after 2000 rds never a failure. I feelits one of the nicest .40 on the market.