Try >>>/diy/
/g/ is full of kids with their gayming graphics cards and expensive smartphones.
Dumb question, but have you tried asking Ingersoll Rand?
>>56600037
Thats a 6" red kind with plastic parts.
>>56599666
Looks like a foam filter element for what appears to be an older version of the F series filter.
>>56599666
not completely sure, but it looks like a water trap. it helps to remove water from compressed air so it doesn't fuck with pneumatic elements. but it should have a purge at the bottom. so it could be a oil deposit that uses venturi effect to lubricate the stuff in the system. maybe the visor at the side is to check if you have you refill the oil.