I'm away from my home computer – in Philadelphia while my wife, the eponymous Rebbetzin, takes an exam here – and so I can't type in Hebrew for this post.
For whatever it's worth, Philadelphia strikes me as odd; having walked the streets a bit today, I found fewer smiles than I expected (I've seen many more on the streets of Manhattan), and more cigarettes than I expected.
In any case: On to the Daf. As usual, please read with a gemara in front of you, for maximum clarity.
Tosafot b'Shlichut appears to have a good approach to the “b'shlichut b'al korchah” line, with Rabbeinu Chananel's explanation. However, as Tosafot notes at the end, the language doesn't really match.
The company we keep - The gemara here discusses signing a document along with a Kuti witness, where one knows that this Kuti is careful about mitzvot. The Kuti witness is accepted, because we assume the righteous witness would not have signed without checking the legitimacy of the Kuti witness.
This is interesting, in light of Sanhedrin 23a and Shevuot 30b in which we discuss the idea that one should not sign a document along with a problematic witness (or sit on a beit din with a problematic judge). The Sanhedrin source is stricter than Shevuot; Shevuot indicates that I could sign with another party if I didn't know that person's status (which would ruin our gemara's assumption regarding the Kuti, unless we would say that default Kuti status is that of a rasha), but Sanhedrin requires that I actually know he is righteous.
See also the difference between Mishneh Torah Hilchot Sanhedrin 2:14 and 22:10.
For more on this issue, see Meiri on that gemara in Shevuot, Perishah to Choshen Mishpat 7, and Yabia Omer 2:Choshen Mishpat 1.
Note that, once again, Abayye presents an explanation which does not match our gemara's edition, and Rava calls him on it. However, Rava explicitly alters the edition, with a 'chisurei mechsira' argument.
Note that the gemara's interpretation of “lo telaket le'ani” is explicitly against the te'amim of the trop.
Divine mercy - The last Rashi on the page is extremely interesting; Rashi says that Gd will have mercy upon an eved because the eved is obligated in some mitzvot. This is problematic in light of Tehillim 145:9, a sentence cited as law in gemara and Rambam, which says, “Gd's mercy is upon all of His creations!”
See Tosafot Chada
On the third line – it should say 'nihalayhu'
Note that both Rav Natan and “Yesh omrim” appear in the same machloket here, although the gemara elsewhere (end of Horiyyot) identifies them as one and the same. Tosafot somewhere (I am without my library, but it may be the Bava Batra reference in the margin on this page) suggests that statements made by R' Natan early in his career, before he received this moniker, are cited with his given name.
See Tosafot “vaChachamim Omrim” on the interesting question of how money is handled in civil cases, where the verdict is “Teiku.”
Rashi and Tosafot have a fascinating debate here, and in Ketuvot 85b, on what the gemara is recommending when it authorizes a judge to do “shuda” - to use his discretion.