Final revision to design - which included replacement of 7,5 cm cannon with 8,8 cm one and a significant further weight increase - was due to T-34 and KV-1, but that does not make Tiger a direct response to KV-1.
The reason the Tiger got that last revision was because the 88mm gun was not 100% reliable against the KV-1... there was a situation where a KV-1 stayed behind at an arterial road fork on soft terrain where driving tanks off road was simply not an option. The KV-1 held up the german unit for critical days where they would send in their tanks with 50mm guns and short 76mm guns which didn't do anything, and 88mm guns were destroyed being moved up along with their trucks. They tried satchel charge attacks on the tracks and the gun barrel at night only to be repelled by machine gun fire from the tank. Eventually they managed to distract the KV with an attack by light tanks and were able to set up an 88mm gun and fired 6 rounds to silence the KV. When they approached they found only two of the 88mm rounds even penetrated the tank and the machine guns opened up on them. Apparently a german solider managed to throw hand grenades into an open hatch to eventually defeat the vehicle.
This was from German records.
I think it would be fair to say that German intelligence failed big time. They not only underestimated the total number of Soviet tanks that was available at the start of the war, but they also had no idea that the T-34 and KV-1's even existed despite the fact that they were already being produced.
After WWI the Germans and Soviets secretly cooperated in a range of fields including armour design but that cooperation and assistance ended in 1933 when Hitler seized power.
There was no cooperation after that.
The non aggression pact is a non aggression pact... you would not need a non aggression pact with an ally.
At the start of the war German tanks were poorly armed and had terrible armour. The only tank of note was the PzIV but it was produced in small numbers as an infantry support tank.
Even with poor armour and not so great guns they were well laid out with the clear roles for each crewman without overloading them with jobs. A gunner just fired the gun, the loader loaded the round the commander told him to load, the driver drove, the commander looked for threats and targets and commanded the vehicle... telling the driver where to go and the gunner what to shoot and the loader what ammo to load.
The initial success of the Nazis was due to the superior organization of the Germans and the inferior organization of their opponents.
Coordination of their forces was important... their air force was essentially their tank artillery support, while their actual artillery walked miles behind... the armour rushed ahead and found gaps in fronts and punched through... any powerful position was bypassed and left for infantry and artillery to reduce, while the armour moved forward and took out enemy rear positions and support and supply train...
The Germans didn't have half tracks till much later in the war and there is a reason no one uses half tracks these days... they are awful.
I'd say most important piece of equipment in German arsenal early in the war was radio. All German tanks had it, while during Battle for France and early in invasion of USSR, Allied tanks usually had one radio per every 4 to 5 tanks.
The irony is that the USSR probably had as many radios as Germany did, but they had 10 times as many tanks so one in 9 tanks with a radio... meaning the commanders vehicle had a radio.
Having radios in vehicles sounds important but actually having better optics and better guns would be more valuable... Aircraft would benefit more from having radios than most tanks would.
What would you expect them to use the radios for? Look out behind you... there is a German tank... In the dust and smoke of a battle you are not going to know where everyone in your tank unit is.... so how is a radio going to help... apart from letting you hear the screams of crews getting killed?
Having three man turrets with a gunner and a loader and a commander is much more use than having a radio.