Why does the Torah insert the (otherwise superfloous) words "Vekar'u eilav ... "?
Yevamos, 101b: To teach us that the Zekenim must speak to him, and not their Sheluchim.
What are the implications of "Ziknei Iyro"?
Yevamos, 101a: It implies even if they are Hedyotos (who are not Talmidei Chachamim) - they are permitted to act as a Beis-Din for Chalitzah. 1
Refer also to 25:7:2:1:1.
Sanhedrin, 31b: It implies that the Yevamah musqt go after the Yavam to release her and not vice-versa. 2
What do the elders say to the Yavam?
Yevamos, 101b: They advise him that, if he is much younger than her or if she is much younger than him, he should marry someone his own age 1 and not bring strife into his home (by performing Yibum).
And perform Chalitzah.
What are the implications of "Ve'amad" and of "Ve'amar"?