The whole line up of later Leotax bodies can become quite confusing as their designations can seem quite similar. Starting with the TV, released in 1957, which is 1/500 sec and self timer. It was followed in 1958 with the T2, 1/500 sec and no self timer. Then the K3, 1/500 sec, no self timer, no slow speeds. In 1958, the FV was released with 1000/sec top speed and self timer. It was soon followed by the TV2 (Merite), 1500/sec and self timer. This camera was never called the Merite until the T2L (Elite) was released in 1959 which had 1/500/sec and self timer. Last but not least, the final Leotax G was done but very few were sold or produced as Leotax fell victim to the Japanese camera recession of 1960 which took down many companies which had produced cameras through the 50's.
As to the 5cm/F2.8 lens, I can't add much as the description provided pretty much gives it's specs. I know it is a very good lens, as I have one, but truly how much better than the Topcor 5cm/F2, or the very rare Topcon 5cm/F1.8, I can't comment. Love all the Topcor lenses of the period as I have the 3.5cm/F2.8, the two 50's mentioned, a 9cm/F3.5 and a quite rare 135.5cm/F3.5.