Did the people actually donate goats?
Rashi (citing Targum Onkelos) and Targum Yonasan: "ve'Izim" refers, not to the goats themselves, but to goat's-hair. 1
Rashi: Since Targum Ohkelos (and Targum Yonasan) writes 'me'Azei", with a 'Mem'. See also Sifsei Chachamim.
What is the definition of "Techeiles", "Argaman" and "Tola'as Shani"?
Yevamos, 4b: Based on the known fact that "Sheish" is linen and all the Bigdei Kehunah are either wool or linen, they are all woolen threads; "Techeiles" is dark blue, "Argaman", purple and "Tola'as Shani", crimson. 1
Seeing as they brought, not goats, but goat's-hair, why does the Torah write "Izim"?
Sifsei Chachamim: Because the women spun it directly from the goats' backs. 1
What is the definition of "Tola'as Shani"?
Targum Onkelos and Targum Yonasan: It is wool that has been dyed with a crimson dye
Yerushalmi Kil'ayim, 9:1: It is wool that has been dyed with the blood of a crimson worm 1 or the blood of any living creature (like the worm).
See Torah Temimah, note 4, who cites the Rambam and elaborates. 25