Why did he bring Matzos?
Rashi: It was Pesach 1 , the day that the Omer is waved. This is why it says "v'Hinei Tzelil Lechem Se'orim Mis'hafech" 2 (7:13), for the Omer is brought from barley.
R. Yeshayah: He rushed to make it; it did not have time to ferment.
Refer to 6:13:2:1. Even if it were not Pesach, he should bring Matzah, for all Menachos are of Matzah! Chametz is forbidden, except for Shtei ha'Lechem and one kind of Lachmei Todah; no part of them goes to Hashem! Gid'on did not bring a real Minchah, which is from Soles (fine flour), and not Kemach. Also, he did not slaughter the goat l'Shem Korban and throw its blood. If it were not Pesach, also Chametz would have been permitted. (R. Yeshayah clearly holds like this; refer to 6:19:1:2. - PF)
The Omer is waved on the second day. In between, Gid'on sent Sheluchim to recruit men from three Shevatim, and Hashem gave to him signs through dew on two nights! Perhaps Hashem defeated Midyan via barley in the merit that Yisrael offered the Omer shortly before this. (PF)
What is "ha'Marak"?
Rashi: It is the liquid (in which it was cooked). 1
Radak: This is because [the liquid] has Miruk (dissolved) meat and what comes from it.
Why did he bring the goat and the liquid?
Malbim: He did not know if it will be accepted for a Korban to Hashem, or if it will be consumed, like the angels ate Avraham's food. Therefore he brought meat and liquid, which are proper for a Korban and for eating. 1
Perhaps he means that meat is proper for a Korban and the liquid for eating. Why does he mention the angels who visited Avraham? Avraham did not intend for a Korban. They 'consumed' the food because they took the guise of people! (PF)
What is Parur?
Radak: It is a copper pot in which meat is cooked.
