I guess the only things to do are to quote the subject line in another area of the forums, "Why is everybody a plumber?", and wonder if plumbing is the only thing people become experts in after reading a book, and asking a friend some questions.
If I had a friend whose father was a brain surgeon, I would NOT let him work on my head. Knowledge is not passed by heredity or osmosis, so unless the friend was ALSO A PLUMBER, why would you ask him ANYTHING about plumbing?
1. where do you intend to connect it to?
2. If you are going to connect it to the 4" vertical line, it is too far away unless you add its own vent.