What If: Germany never invades the Soviet Union

Exactly. War would've happened anyways, only in this scenario you have a more prepared USSR and a Germany on the defensive.
How well will Germany do in that situation? Also, will they be seen as victims on the world stage and perhaps receive some version of Lend Lease?

I'm seen this suggested before but whether the Soviets had anything more than contingenty plans I don't know. Like the US's infamous colour plans most country would have plan for war with assorted neighbours. If nothing else it is a good exercise for staff officers working out the details and considering implications. Its only if they become so embedded in the military planning, thee classic example being the Schlieffen Plan in Germany, that their a serious problem. .

If Russia attacked Germany, at least before Germany is on the rack, then their likely to face serious problems. While the Winter War highlighted some problems and the German attack in 41 caught the Soviets in the midst of a reorganisation I suspect that even in say 43 or 44 the Soviets are likely to have a lot of problems. By weight of numbers they could make fairly deep inroads but I suspect that they would be thrown back after the initial impluse. After that this could become a very bloody war that is likely to end with both sides being exhausted and the region of conflict to be seriously devastated. I would suspect this would be Poland, eastern Romania and neighbouring areas of the Baltic States, Byorussia and the Ukraine.

Much would depend onwhat the state of the war between German and Britain was, especially if the US had joined the latter. If that was the case I suspect they would hold their breath and 'welcome' the Soviets as 'allies' although they might well not send any aid, as there would seem to be no need and Stalin probably wouldn't welcome any. This might change if the Soviets start doing badly but I doubt they would do as badly as OTL so there would be little motive for the west to seek to aid the Soviets.  I can;t see any way that the US would send aid to the Nazis.

I would expect that the Soviets would attack Romania and that Bulgaria and Hungary, plus possibly Italy would aid in fighting the Soviets. Both because they would be seen as a way of flanking any German defences further north, of denying German Romanian oil and they would expect Romania and the other Balkan states to support Germany.

I also agree.
I wonder if Stalin's position would be as secure. In OTL he had the support of the entire country. Would he face a revolution like 1917 if he pushed the country to collapse as the aggressor?