綠卡或公民權 is granted at the disrection of USCIS. there is no guarantee.
Right to vote is only for US citizen. US contitution (Amendments) protects immigrants or intending immigrants from discrimination by governments (Feds and State)even private entity under the equal protection clause, but language of the US contitute does not mention anything about the right for citizenship or GC.
Suing USCIS for damages due to delay or wrongdoing on an applicant's case is applicable, there are cases, such as when an immigration judge's conduct or decision review bias or discrimination, civil remedy could be granted, including attorney/legal fees. The monetary remedy are not under any immigration related law or code, but is just a form of civil suit.
Trial lawyers who do not practice immigration may not perform well concerning immigration issues. Knowledge is accumulated, and could not be learnt in a few minutes. Even the best criminal trial lawyer would easily fail the immigrants case for the oral agruments in Federal Circuit Courts.
As for immigration lawyers, there are different types. litigators who go to immigration court and other court on daily basis and general practitioners who only do general filings, motions and petitions without any court appearance. An oral agrument is always asked on all petitions and appeals. However, most of the cases are resolved without oral argument and settlement with US attorneys, including a Writ of Mandamus action.
Genearlly, WOM applicants will always ask for award of attorney fees as one of the remedies.
The best immigration lawyer is the one who saved their client time and monetary and willing to take less gain to settle the case than going to court for more legal fee.