Various Chemicals Effects on Cognitive Functions? Also Pain Tolerance relation to self infliction...? (will answer yours)?

Warning in advance, this is purely hypothetical research. It is not being used first hand for anything.

So I need to know-

A: How much pain does the human brain generally tolerate before releasing chemicals/ endorphins? Particularly in relation to deliberate self harm-

B: What SPECIFICALLY are these chemicals and endorphins?

C: What effect do these chemicals take on cognitive, creative, and other complex functions of the brain BOTH short and long term? (short term a little more important to know however)

K that was all I needed as far as S.I. Information goes.

I also need to know what chemicals, endorphins, (whatever) are released due to physical exercise such as walking/running and how THOSE effect the brain short and long term.

Same study on Nicotine> amount and type of chemical reaction and short/long term effects.

Finally, I also wanted to answer these same questions on the subject of Adderall.

Please cite information- I want to be able to read most of this myself, but haven't been able to find very knowledgeable sources.

Thank you.