Throughout its service life, the 109 was constantly evolving. The main differences between the variants of which you speak are armament, engine, canopy, and tail. The Hartmann "versions" are most likely markings. To learn more about the differences, a great on-line source is the "109 Lair." I don't know the link off-hand, but a search will most probably locate the site.
I've been doing some serious looking at the plethora of new 1/32 kits that are now available. They DEFINATELY aren't the 1/32 kits that I knew from the sixties. I will most probably get Hasegawa's Bf 109G-6 and FW 190D-9. From what I've seen and read, these are stellar kits.