Those also only give 1 card for delve/Delirium/threshold,where mine could give 2(3 for the surveil 2 version.)
Not relevant.
The requirement is to fuel delve and not fuel it as much as possible.
I will agree that they do not fuel Young Pyromancer so I guess your 2 mana version is a bit stronger than the 0 mana versions. But it also costs 2 more mana. However you are 100 % correct and I do not think anymore that I can find a 0 mana card to will trigger all of the requirements.
I think people will get a shock when they try it out. They will believe they have some efficient filtering in their deck but realize how costly it is to be 1 card down. All comparable cards replace themselves cheaper. The scry and surveil lands are already a card when they are played to the battlefield as a land. Cards like Preordain draws immediately and therefore have value.