1)
Why does it say "v'Atah..."?
1.
Malbim: If you will put your hearts to your ways, you will see that you must build the Mikdash. You will see via experience that your deeds are not accepted!
2)
What is "Al Darcheichem"?
1.
Rashi: On your affairs. You see that there is no Brachah in your deeds - "Zeratem Harbe v'Havei Me'at" (6). All this is due to Churban of My house!
2.
Radak: Your ways, affairs and deeds. This is like "v'Chibadto me'Asos Derachecha" (Yeshayah 58:13). After, it explains - "Zeratem..." (6)
