You seem to be confused about positional righteousness (which is in Christ) and practical righteousness (which is your day-to-day righteousness in word and deed). Unless you claim to be sinlessly perfect (which is claimed by some deluded people), you will sin from time to time (either sins of omission or sins of commission). That will not change your positional righteousness, but it will mean that you have to examine yourself and deal with your present sins. See the first epistle of John.No. In fact, if I was trusting Him and following Him, I would not dare act unrighteously and then say about it, oh well, despite acting unrighteously, I am nevertheless righteous.
Every believer has the imputed righteousness of God and Christ, which is by grace through faith. But that is not a license to sin, but rather an incentive to be holy as God is holy. Nonetheless you will not be totally free from sinning, because the old Adamic sin nature has not been eradicated. See Galatians 5.