For mental checklist guide, these videos are great (each split into multiple parts):
https://www.youtube.com/watch?v=m36B...0A8C8B0A2AE4AB
https://www.youtube.com/watch?v=HzhIjG39Haw
It is just a matter of practice; you will soon stop forgetting things, as they will become a part of your mental routine. Well, to an extent; I, for example, am still pretty terrible at spreading creep.
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For macro-intensity, I'd say they all are comparable. In general, for improving macro, I would give the same recommendation to you as I give to everyone: play Monobattles! Since you only have 1 unit to make and it is hard to forget it, you can concentrate on other things, such as supply, making workers, expanding, scouting, building defenses... Training multiple different units comes naturally after that.