Why does it say "Chemah Ein Li"?
Rashi citing Targum Yonasan: I have no mouth (words) to arouse anger at the Nochrim, for also Yisrael sin, and Midas ha'Din would prosecute.
Rashi citing Avodah Zarah 4a: It refers to Yisrael. With all that they angered Me, I cannot pour My anger on them to eradicate them, due to My Shevu'ah to their fathers.
Radak: This is not among My Midos; rather, I am "Erech Apayim" (Shemos 34:6; slow to anger). Even though it says "Nikem Hashem u'Va'al Chemah" (Nachum 1:2), that is "l'Tzarav" (for His enemies), to bring the day of their demise, like it says there. Even though He delays greatly for them, this is to totally destroy them - "u'Meshalem l'Son'av El Panav Leha'avido" (Devarim 7:10). For Yisrael, when they sin, He punishes bit by bit, and does not guard [the sin] until it will destroy them - "Rak Eschem Yadati mi'Kol Mishpechos ha'Adamah Al Ken Efkod Aleichem Es Kol Avonoseichem" (Amos 3:2).
Malbim: The vineyard says, I have no anger and stored hatred against any nation, only
What is the meaning of "Mi Yitneni Shamir Shayis ba'Milchamah"?
Rashi citing Targum Yonasan: This refers to those whom I fight, i.e. Yishmael. If only I could punish them, and Midas ha'Din would not be able to protest! If Yisrael would repent, I would make [Yishmael] thorns and thistles.
Rashi citing Avodah Zarah 4a: It refers to Yisrael. If only it were like earlier days, without the Shevu'ah - I would make the land thorns and thistles (desolate).
Radak citing his father: The vineyard that gives to me thorns, instead of grapes - if I had anger, I would take one step and burn all of it together in war, when I fight with it for all its sins. It is as if it says Shamir v'Shayis; the prefix Vov is omitted, like "Shemesh Yare'ach" (Chabakuk 3:11).
Malbim: [My anger is only against] one who will fight me, in order to put in My vineyard thorns, which destroy the vineyard.
What is the meaning of "Efse'ah Vah Atzisenah Yachad"?
Rashi citing Targum Yonasan: I would take a step over Midas ha'Din and punish them with extra anger for their sin, and burn them together.
Refer to 27:4:2:3.
Malbim (4-5): I would fight with anger against one who fights me and puts thorns in my vineyard, and burn him and the thorns together. Yisrael will not do evil or fight - but if one dares approach [to fight] them, they will do judgments against him with anger.