Why do the Berachos begin specifically with rain?
Ramban: Because when the rain falls in the right time, the air is pure, the fountains and rivers produce good water, and the land 1 yields a bountiful harvest and the trees a lot of fruit. 2 As a result of all this, the people remain healthy, they and the animals do not lose their babies and they live long lives. 3
What are the connotations of "b'Itam"?
Rashi: "B'Itam" refers to times when people are not in the streets 1 - such as Tuesday night and Friday night.
Targum Onkelos and Targum Yonasan: It means when they are due.
See Sifsei Chachamim.
What is the definition of "Eitz ha'Sedeh"?
Rashi: It means barren trees. 1
Which will bear fruit in the time of Mashi'ach -when the current Berachos will take place (See Sifsei Chachamim).
QUESTIONS ON RASHI
Rashi writes that Eitz ha'Sedeh" is barren trees. "Piryo" implies that they normally bear fruit!
Moshav Zekenim: Perhaps "Piryo" refers to the field (the trees will produce what it is proper for the field to produce).