Why is it necessary to clear the vessels from the house before the Kohen arrives?
Rashi #1: To prevent them from becoming Tamei, because until the Kohen arrives and declares the house Tamei, they are Tahor. 1
Rashi #2: Refer to 14:34:4:1*.
Seforno: It is to allow the owner time to do Teshuvah and for him and the Kohen to pray to Hashem for mercy. 2
Erchin, 16a: Nega'im (on the house) come as a result of Gezel.Consequently, 'He gathered money that was not his, therefore the Kohen comes and scatters his money!'
Seforno: Bearing in mind the immense value of a house as compared to that of a garment. A Midrash says that the sequence of events regarding a stricken house hints at the destruction of the first Beis-ha'Mikdash, its rectification via the building of Bayis Sheni , the destruction of Bayis Sheni and its purification via the building of the third Beis-ha'Mikdash - may it come about speedily in our days. Refer to 14:34:2:3.
Why must the owner remove the Keilim, in case they become Tamei? Why can he not simply Tovel them after they become Tamei?
Rashi: The Torah has pity on earthenware vessels which are not subject to Tevilah and which must therefore be broken, 1 mot like food and drink which can be eaten on the days that the owner is Tamei. 2
Rashi (in Yoma, 39a): If the Torah has pity on small things, how much more so on big ones; if it has pity on the money of the miserly, how much more does it have pity on the money of Tzadikim! Moshav Zekenim - also Tamei Klei Cheres are useful for when he is Tamei! (Perhaps there was a glut of Tamei Klei Cheres; there was no value in having another such Kli. - PF).
According to R. Yehudah in the Sifra, the owner is obligated to remove even bundles of straw and of stubble, which are not subject to Tum'ah. See Oznayim la'Torah, DH 'Ufinu es ha'Bayis'.
What does the Torah mean when it writes "ve'Achar-Kein Yavo ha'Kohen Lir'os es ha'Bayis"?
Oznayim la'Torah: It means that the Kohen must first of all examine the house to ascertain whether it is subject to Nega Batim or not. 1
Why must the owner remove the Keilim , before the Kohen arrives? The Kohen can see it, and be silent until the remove the Keilim . Nothing is Tamei until the Kohen leaves the house and declares it Tamei!
Moshav Zekenim citing R. Yehudah ha'Chasid: The Kohen would not be concerned [to wait until they remove] an Oni's Keilim, only for an Ashir's Keilim , and this is brazen. Therefore, the Torah equated them. 1
The Torah could have equated them, and always said that he may not be Metamei until after they remove the Keilim ! Perhaps it would appear ludicrous, that the Kohen hints that they remove Keilim because it is a proper Nega, and the house is not Tamei yet. (PF)