What is the connection between this Pasuk and the previous one?
Seforno: The nicest way of supporting a needy person is by extending him a free-interest loan.
What is the difference between "Neshech" and "Tarbis"?
Rashi: In fact, the Chachamim equate them, and the Torah gives them two names in order to present them as two La'avin.
Ramban: So-called because the interest grows into a large amount - like the blown-up swelling of a snake-bite. See Ba'al ha'Turim.
Ramban: As is customary with a money loan.
Ramban: As one tends to do with fruit, where Reuven lends Shimon a measure of fruit until the harvest, when Shimon repays a little extra.
Why does the Torah insert the words "Veyareischa me'Elokecha"?
Rashi #1: Because a person is drawn after interest, and it is difficult to break away from it. Moreover, one allows oneself the liberty of taking interest to offset the loss of his money. 1
Rashi #2: It is warning against lending money on interest using a Nochri as a medium. 2 This is a thing that lies in one's heart, since nobody knows the true facts other than Hashem. Therefore the Torah writes "Veyareischa me'Elokecha".
And what are the ramifications of the phrase "ve'Chei Achicha Imach"?
Ramban: Refer to 25:35:1:1*.
Ramban #2 (citing Bava Metzi'a, 62a): It implies an obligation to return a fixed Ribis to the borrower, to enable him to live.
Seforno: It implies that one is only obligated to lend a needy person money if, after extending the loan, one has enough to live on oneself. 1
Rashi (in Kesuvos 15b) and Targum Onkelos: It is a Mitzvah to sustain one's fellow-Jew.
It is a reason for the prohibition against taking interest - because he is your brother and you would not lend your brother money on interest.
Seforno: As the Gemara states in Bava Metzi'a, 62a 'Your life takes precedence over somebody else's.