I would agree re: gang affiliation, don't forget other possible grounds of inadmissibility, Neo-Nazi tattoos, communism, etc type of tattoos; see the questions on the I-485 application and this will give you some idea of the type(s) of affiliations
No attorney-client relationship is created or implied by this communication in any way. Consult a competent immigration attorney preferably one who is a member of the American Immigration Lawyers Association (AILA).
No. This is not an issue unless the tattoos look like gang tattoos. This can cause a delay. Hopefully, you know the difference. Good luck.
This is general information, not legal advice, and does not create an attorney client relationship.