[Radoye]

Quite right. The so called "He-100D" was actually a propaganda designation involving a photograph of the twelve preproduction He-113 fighters developed from the He-112 (which entered limited production and was service tested alongside the BF-109 development models in Spain, 30 of the He-112 were built).

The He-113 was effectively Heinkell's competitor to the Fw-190 as a potential successor to the Me-109 but engine manufacture was a serious issue at the time and one of the main reasons Tank's unconventional radial proposal made the grade was that it used a different one to other planes in service (shortage of Daimler-Benz and Junkers motors was an issue which plagued German aircraft manufacture for some time, just about everything used those motors if it wanted good performance).

No - He-110 was the official designation of what used to be known He-113, Heinkel changed the name because of superstition (number 13). The planes were not adopted by the LW but flew in the private Heinkel factory defense unit. Despite this, more than a hundred "He-110" kills were claimed by Allied pilots during the war.

One He-110 was sent to USSR for evaluation, before Barbarossa when Hitler and Stalin were still pals. IIRC it was tested by Yakovlev people.

He-110 was not a FW-190 competitor, instead it was built to address the shortcomings of He-112, mainly too complex and expensive manufacture and maintenance (the performance of 112 was actually marginally better than that of the Messer but was too complex so LW thought it was not worth it, 109 already being far superior than anything available to the potential enemies). He-100 was therefore designed to be as simple as possible yet to offer good performance. However, LW once again refused to adopt a Heinkel design (a thing that was to repeat itself a few more times during the war, some say because Heinkel himself was not a Nazi and Wily Messerschmidt was - both He-100 and Fw-187 were killed off around the same time due to politics, because Wily Messerschmidt was well connected) this time the explanation was that it would be too big of a disruption to the production if they stopped to re-tool the factories for the new fighter, besides 109's were still superior to everything Allies could throw against them at the time.

But, if they decided differently, unlike FW-190 the He-100 would actually be ready for service in time for the Battle of Britain where its better range compared to 109 could be very useful indeed.