As for the former, I recommend taking notes diligently while studying/learning new topics and filing these notes appropriately where you make consulting the original material be it YT videos, online tutorials/posts, articles or books unnecessary since your notes are more than enough and are kept up-to-date accordingly; adding, removing or archiving as you deem necessary.
As for the latter, I struggled with this lately but I think that I made some progress to overcome this roadblock by making snap decisions on the spot by resorting to the old trick of "heads or tails" everytime I start to overthink a solution, and for more overwhelming alternatives, I built a custom randomizer that's fed a list of choices, and then spits the decision that I should make, and I comply with its wish enthusiastically every time.
I wouldn't say that this is the most efficient decision making process out there but for me action is always far better than inaction, and I don't think that perpetual state of deliberations and contemplation was any better as it hindered any progress to be made in the name of picking the most rational or efficient course of action to be taken which it didn't seem to emerge no matter how hard I tried to think a way out of it.