I replied to your PM and to your post on the other forum, where I gave you the best answer I could to your first two questions.
I assume you saw it and thats why you're here?
As I said to you, there are no truly definitive answers to your questions.
Mostly there are a lot of differing experiences from individuals doing/wearing the exact same thing.
Its best that you read as many posts and threads as possible to gather a concensus of opinions & knowledge.
As I said to you before, you should read about Receded93's experiences because they probably match your situation more closely.
I'll give you the links again here:
As for products, there is a huge range of products that are ok to use on a hair system and equally a huge range of ones that can dry out the hair itself or negatively effect the adhesion of your attachment.
I can answer your last question.
No, it wouldn't come off if someone yanked your hair a little or if it's really windy or if you wore a hat.