How do the verses teach that Stam Yad is the left?

Rashi: Because it says Yad and Yemin, Yad must be the left.

Etz Yosef: "Yadah la'Yased Tishlachnah" means that she held the peg with one hand; "vi'Yminah Lehalmus Amelim" must mean that she hit it with the other hand until it passed through his head.

Here we say that Stam Yad is the left. Above (10a), the extra "Yad" written about a Metzora teaches that "va'Ymalei Kapo" regarding Kemitzah is with the right hand. We should rather learn from it Yad of Tefilin (the same word), and not Kapo of Kemitzah!

Tosfos: It is better to learn Avodah from Avodah. However, why don't we learn both of them? Perhaps we do not, for there it is the hand, and here it is the upper arm.

Daf Al ha'Daf citing Beis Aharon v'Yisrael (22:2 p.144): One who blesses on food holds it in his right hand (OC 206:4), and all the more so a Mitzvah (Pri Megadim, Eshel Avraham 6). Hash-m told Moshe to take [his staff, which became a] snake via "Yadecha", and so he did. Based on our Gemara, this was the left hand. This was a Mitzvah! Similarly, why did Avraham send "Yado" to slaughter Yitzchak, and Pinchas took a spear "b'Yado"? We can resolve according to Hagahos Maharsham in Menachos. (NOTE: I could not find this. Perhaps we learn only to Mitzvos that apply for generations. - PF)

Why was he called R. Yosi ha'Chorem?

Rashi: His nose was recessed; this is the Mum Charum (Bechoros 43b).

Tosfos: It is astounding to say that he received a nickname of disgrace!

Tosfos: It is based on his place.

We find that the right hand is called Yad Stam - "va'Yismoch Yad Aviv"!

Tosfos: The first Tana explains that there is different, for above it said Yad Yemino. However, R. Yosi holds that even so, due to this we cannot learn from Yad of Metzora.