Around the Jewish Year

Is there a special blessing we're supposed to say for the first rainfall?

Is it permissible to weave a mat from the lulav leaflets or, alternatively, to throw the lulav away in the garbage? Similarly, would it be permissible to build furniture from planks used to place sechach on?

I see that it says on all the etrog boxes “not grafted.” What exactly does that mean?

Can I sell products containing wheat protein (like soluble soup mix) together with the chametz?

I just bought some flower seeds, and I was wondering if I'm allowed to plant them now. I looked at the Shulchan Aruch and I wasn't quite sure I understood what it meant that you're not allowed to plant "a king's garden." 

Whoever sees especially beautiful creations recites the blessing shekacha lo ba'olamo; "Who has such things in His world."
Whoever goes out to fields or gardens in the days of Nissan and sees trees blossoming and budding recites birkat ha'ilanot, the blessing for the trees: "Blessed … who has withheld nothing from His world, and has created in it beautiful creatures and trees for human beings to enjoy.'"  What is the difference between both blessings?

Can one say birkat ha’ilanot on trees grafted in a forbidden fashion?

I have blueberries growing in a planter in my garden. Last year, I was told I need to count orlah years for it, which seems to make it a tree. If it has flowers, can I count it as one of the trees for birkat ha'ilanot?

Can we say birkat ha'ilanot on a tree with buds that resemble white balls, whose petals have not opened yet, or is it necessary to see the petals of the flowers? We have an orange tree in this state now.

Are gluten-free products kosher for Pesach?