Twice in the week (dis tou sabbatou). One fast a year was required by the law (Lev 16:29; Num 29:7). The Pharisees added others, twice a week between passover and pentecost, and between tabernacles and dedication of the temple.
I get (ktōmai). Present middle indicative, not perfect middle kektēmai (I possess). He gave a tithe of his income, not of his property.