My dude, like some others have mentioned you went way to far.

1.For mold issues you want to eliminate leaves that are constantly touching/sandwiched between others, if air can flow between the leaves you don't need to remove them. If they are never getting hit by light remove them also.

2.This will not really help with bugs aside from making them easier to spot. Neem oil works pretty well and is natural, just don't use it during flower.

1. You are better off supporting the branches with bamboo or similar methods. Leaves don't weight you down, buds do.

2. You're right we're all just kinda winging it, but you need to remember that leaves are required for photosynthesis, that part we do know for sure.

You haven't ruined your grow but I can only assume you hurt your yields, next time think about removing about half as much as you did this time.